Throughput-scalable analytical system using transmembrane pore sensors

ABSTRACT

The present disclosure describes a throughput-scalable sensing system. The system includes a plurality of semiconductor dies sharing a common semiconductor substrate and a plurality of transmembrane pore based sensors configured to detect a change of current flow as a result of analyzing biological or chemical samples. Two immediately neighboring transmembrane pore based sensors are arranged on respective two semiconductor dies separated by a dicing street. Each transmembrane pore based sensor is arranged on a separate semiconductor die of the plurality of semiconductor dies. At least one transmembrane pore based sensor includes one or more detection electrodes disposed above the common semiconductor substrate and a lipid bilayer disposed above the one or more detection electrodes.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to biomedical sample analyticalsystems and, more specifically, to high throughput systems for providingscalable, high speed, and high throughput molecule detection andanalysis.

BACKGROUND

Biological sample analytical systems are used for various applicationssuch as nucleic acid sequencing applications. Some of these applicationsmay require high throughput and throughput scalability, thusnecessitating an increased pixel array size for sensors (e.g., imagesensors) used in such applications. In existing analytical systems, thetraditional way to obtain a large pixel array size for an image sensoris to customize the design of the image sensor according to thethroughput requirement. For example, for an application that requires aCMOS (complementary metal-oxide-semiconductor) image sensor to have aparticular pixel array size, a designer would need to customize orcompletely re-design an existing image sensor having a smaller pixelarray size. For a large pixel array size image sensor, the re-design ofthe image sensor may require not only incorporating more photodiodes inthe image sensor, but also re-designing signal processing circuitry suchas drivers and readout circuits that are necessary for processingelectrical signals generated by the photodiodes.

SUMMARY OF THE DISCLOSURE

Re-designing an image sensor for a specific application may involvechallenging design tasks, extended time-to-market due to design-testingcycles needed for fabricating working semiconductor sensor chips, andconsequently higher re-design costs. Moreover, the costs of re-designcan quickly rise to an impractical or prohibitive level if there aremany specific system throughput requirements necessitating differentpixel array sizes for different applications. Further, the traditionalapproach of re-designing image sensors may be associated with poorsystem scalability. For example, if an image sensor manufacturer hasdifferent analytical products targeting dozens of different markets orapplications, image sensors with different pixel array sizes may need tobe designed separately. But the design of a smaller pixel array sizeimage sensor may not be easily adapted or scaled to obtain a design of alarger pixel array size image sensor. Thus, the traditional way to scalea design of a smaller pixel array size image sensor to that of a largerpixel array size image sensor is often inflexible, inefficient, andcostly. Therefore, it is desired to have a throughput-scalable sensingsystem that has a faster design turn-around time, high scalability, moredesign-efficiency, and more cost-efficiency.

The following presents a simplified summary of one or more examples inorder to provide a basic understanding of the disclosure. This summaryis not an extensive overview of all contemplated examples, and is notintended to either identify key or critical elements of all examples ordelineate the scope of any or all examples. Its purpose is to presentsome concepts of one or more examples in a simplified form as a preludeto the more detailed description that is presented below.

In accordance with some embodiments, a throughput-scalable image sensingsystem for analyzing biological or chemical samples is provided. Thesystem includes a plurality of image sensors configured to detect atleast a portion of light emitted as a result of analyzing the biologicalor chemical samples. The plurality of image sensors is arranged on aplurality of wafer-level packaged semiconductor dies of a singlesemiconductor wafer. Each image sensor of the plurality of image sensorsis disposed on a separate wafer-level packaged semiconductor die of theplurality of wafer-level packaged semiconductor dies. Neighboringwafer-level packaged semiconductor dies are separated by a dicingstreet; and the plurality of wafer-level packaged semiconductor dies anda plurality of dicing streets are arranged such that the plurality ofwafer-level packaged semiconductor dies can be diced from the singlesemiconductor wafer as a group.

In accordance with some embodiments, a throughput-scalable chemicalsensing system for analyzing biological or chemical samples is provided.The system includes a plurality of chemically sensitive sensorsconfigured to detect ion concentration. The plurality of chemicallysensitive sensors is arranged on a plurality of wafer-level packagedsemiconductor dies of a single semiconductor wafer. Each chemicallysensitive sensor of the plurality of chemically sensitive sensors isdisposed on a separate wafer-level packaged semiconductor die of theplurality of wafer-level packaged semiconductor dies. Neighboringwafer-level packaged semiconductor dies are separated by a dicingstreet; and the plurality of wafer-level packaged semiconductor dies anda plurality of dicing streets are arranged such that the plurality ofwafer-level packaged semiconductor dies can be diced from the singlesemiconductor wafer as a group. At least one chemically sensitive sensorof the plurality of chemically sensitive sensors includes a plurality ofion-sensitive field effect transistors (ISFETs). At least one of theplurality of ISFETs includes a semiconductor substrate, a floating gatestructure disposed above the semiconductor substrate, and a dielectriclayer disposed above the floating gate structure. One or more wells aredisposed above or at least partially inside the dielectric layer. Atleast a portion of the biological or chemical samples is disposableinside the one or more wells.

In accordance with some embodiments, a throughput-scalable sensingsystem for analyzing biological or chemical samples is provided. Thesystem includes a plurality of transmembrane pore based sensorsconfigured to detect a change of current flow as a result of analyzingthe biological or chemical samples. The plurality of transmembrane porebased sensors is arranged on a plurality of wafer-level packagedsemiconductor dies of a single semiconductor wafer. Each transmembranepore based sensor of the plurality of transmembrane pore based sensorsis disposed on a separate wafer-level packaged semiconductor die of theplurality of wafer-level packaged semiconductor dies. Neighboringwafer-level packaged semiconductor dies are separated by a dicingstreet; and the plurality of wafer-level packaged semiconductor dies anda plurality of dicing streets are arranged such that the plurality ofwafer-level packaged semiconductor dies can be diced from the singlesemiconductor wafer as a group. At least one transmembrane pore basedsensor of the group of transmembrane pores based sensors includes asemiconductor substrate and one or more detection electrodes disposedabove the semiconductor substrate. The one or more detection electrodesare capable of detecting the change of current flow. The at least onetransmembrane pore based sensor further includes a lipid bilayerdisposed above the one or more detection electrodes. The lipid bilayerincludes one or more transmembrane pores positioned corresponding to thepositions of the one or more detection electrodes.

In accordance with some embodiments, a throughput-scalable photonsensing system for analyzing a biological or chemical sample isprovided. The system includes a plurality of photon detection sensorsconfigured to perform a single molecule analysis based on the biologicalor chemical sample. The plurality of photon detection sensors isarranged on a plurality of wafer-level packaged semiconductor dies of asingle semiconductor wafer. Each photon detection sensor of theplurality of photon detection sensors is disposed on a separatewafer-level packaged semiconductor die of the plurality of wafer-levelpackaged semiconductor dies. Neighboring wafer-level packagedsemiconductor dies are separated by a dicing street; and the pluralityof wafer-level packaged semiconductor dies and a plurality of dicingstreets are arranged such that the plurality of wafer-level packagedsemiconductor dies can be diced from the single semiconductor wafer as agroup. The system further includes a first optical waveguide configuredto deliver an excitation light along a longitudinal direction of thefirst optical waveguide. The system further includes one or more secondoptical waveguides disposed above the first optical waveguide and one ormore wells disposed in the one or more second optical waveguides. Theone or more wells being configured to receive the biological or chemicalsample. The system further includes one or more light guiding channelsconfigured to direct photons emitted as a result of the single moleculeanalysis to one or more corresponding photon detection sensors of theplurality of photon detection sensors.

In accordance with some embodiments, throughput-scalable photon sensingsystem for analyzing biological or chemical samples is provided. Thesystem includes a plurality of photon detection sensors configured toperform a single molecule or cluster sequencing analysis based on thebiological or chemical samples. The plurality of photoelectron countingsensors is arranged on a plurality of wafer-level packaged semiconductordies of a single semiconductor wafer. Each photon detection sensor ofthe plurality of photon detection sensors is disposed on a separatewafer-level packaged semiconductor die of the plurality of wafer-levelpackaged semiconductor dies. Neighboring wafer-level packagedsemiconductor dies are separated by a dicing street; and the pluralityof wafer-level packaged semiconductor dies and a plurality of dicingstreets are arranged such that the plurality of wafer-level packagedsemiconductor dies can be diced from the single semiconductor wafer as agroup. At least one photon detection sensor of the plurality of photondetection sensors includes a plurality of sub-diffraction limit (SDL)photosensitive elements. Each SDL photosensitive element is sensitive toa single photoelectron. A single image pixel is generated based on oneor more two-dimensional or three-dimensional arrays of outputs generatedby SDL photosensitive elements.

In accordance with some embodiments, a method for fabricating athroughput-scalable sensing system is provided. The method includesreceiving a first semiconductor wafer and second semiconductor wafer.The first semiconductor wafer includes a semiconductor substrate and aplurality of sensors disposed in the semiconductor substrate. Eachsensor of the plurality of sensors is disposed in a separate wafer-levelpackaged semiconductor die of the first semiconductor wafer. The methodfurther includes bonding the first semiconductor wafer to the secondsemiconductor wafer; and preparing the bonded first semiconductor waferand the second semiconductor wafer for conductive path redistribution.The method further includes forming one or more redistribution pathsfrom a plurality of electrically-conductive pads disposed at a firstsurface of the prepared first semiconductor wafer to a plurality ofelectrically-conductive spheres disposed at a first surface of theprepared second semiconductor wafer. The one or more redistributionpaths are partially enclosed by one or more through-hole vias. Themethod further includes dicing an array of wafer-level packagedsemiconductor dies as a group from the plurality of wafer-level packagedsemiconductor dies. The array of wafer-level packaged semiconductor diesincludes a group of sensors associated with the throughput-scalablesensing system.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the various described aspects, referenceshould be made to the description below, in conjunction with thefollowing figures in which like-referenced numerals refer tocorresponding parts throughout the figures.

FIG. 1 is a block diagram illustrating a top view and a cross-sectionalview a prior art image sensing system.

FIG. 2A illustrates an exemplary semiconductor wafer map.

FIG. 2B illustrates an exemplary group dicing plan for dicing multiplewafer-level packaged semiconductor dies from a semiconductor wafer asgroups.

FIG. 2C illustrates a throughput-scalable image sensing system obtainedbased on group dicing wafer-level packaged semiconductor dies from asemiconductor wafer.

FIG. 3 is a block diagram illustrating an exemplary throughput-scalablesensing system.

FIG. 4A is a cross-sectional view illustrating an exemplary fluidicreaction channel and a waveguide-based optical system disposed acrossmultiple sensors in a throughput-scalable image sensing system.

FIG. 4B is a cross-sectional view illustrating an exemplary fluidicreaction channel with direct illumination across multiple sensors in athroughput-scalable image sensing system.

FIG. 5A illustrates an exemplary image sensing system with across-sectional view of an embodiment of a TSV packaged back-sideillumination (BSI) based image sensor.

FIG. 5B illustrates an exemplary image sensing system with across-sectional view of another embodiment of a TSV packaged BSI-basedimage sensor.

FIG. 5C illustrates an exemplary image sensing system with across-sectional view of an embodiment of a TSV packaged front-sideillumination (FSI) based image sensor.

FIG. 5D illustrates an exemplary chemical sensing system with across-sectional view of an embodiment of a TSV packaged ion-sensitivefield effect transistor (ISFET) based sensor.

FIG. 5E illustrates an exemplary sensing system with a cross-sectionalview of an embodiment of a TSV packaged transmembrane pore based sensor.

FIG. 5F illustrates an exemplary photon sensing system with across-sectional view of an embodiment of TSV packaged photon detectionsensor capable of performing a single molecule analysis.

FIG. 6 is block diagram illustrating the operation of an exemplaryevent-triggered shutter.

FIG. 7A illustrates an exemplary quanta CMOS image sensor (QIS) basedsensing system with a cross-sectional view of an embodiment of a TSVpackaged QIS sensor.

FIG. 7B illustrates an exemplary QIS photosensitive element.

FIG. 7C illustrates another exemplary QIS photosensitive element.

FIG. 7D illustrates an exemplary signal processing circuitry forprocessing outputs of a QIS.

FIG. 7E illustrates wafer-level prospective diagrams and correspondingblock diagrams of an embodiment of an exemplary QIS-based sensingsystem.

FIGS. 8A-8G illustrate cross-sectional views associated with processingsteps for fabricating a throughput-scalable sensing system.

FIG. 9 is a flow chart illustrating a method for fabricating athroughput-scalable sensing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well-known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Exemplary sample throughput-scalable sensing systems will now bepresented with reference to various elements of apparatus and methods.These apparatus and methods will be described in the following detaileddescription and illustrated in the accompanying drawing by variousblocks, components, circuits, steps, processes, algorithms, etc.(collectively referred to as “elements”). These elements may beimplemented using mechanical components, optical components, electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Further, the same or similar elements illustrated in thedrawings are labeled with the same reference numbers. Different elementsmay be labeled with different reference numbers.

Although the following description uses terms “first,” “second,” etc. todescribe various elements, these elements should not be limited by theterms. These terms are only used to distinguish one element fromanother. For example, a first semiconductor wafer could be termed asecond semiconductor wafer and, similarly, a second semiconductor wafercould be termed a first semiconductor wafer, without departing from thescope of the various described examples. The first semiconductor waferand the second semiconductor wafer can both be semiconductor wafers and,in some cases, can be separate and different semiconductor wafers.

The throughput of a traditional image sensing system is typically notscalable or easily scalable. Scaling the throughput of such atraditional system often requires complex and costly re-design,especially if there are multiple throughput requirements to be satisfiedfor different sensing systems or applications. Further, traditional wirebonding technologies for packaging such a sensing system may also imposeobstacles or difficulties for scaling the throughput of the sensingsystem. For example, as described in more detail below, traditional wirebonding technologies may not be suitable for large scale image sensingsystem that has a large pixel array size and may further complicate thedesign of a system for disposing sample channels and/or optical systemsacross multiple image sensors.

In this disclosure, various embodiments of throughput-scalable sensingsystems are provided. These systems implement wafer-level packaging ofmultiple sensors disposed on multiple semiconductor dies. The multiplesemiconductor dies and a plurality of dicing streets are arranged suchthat the multiple wafer-level packaged semiconductor dies can be dicedfrom a single semiconductor wafer as a group. Based on the throughputscaling requirement for the sensing system and based on a throughputcapacity of each sensor, the number of sensors in the sensing system canbe readily determined. As a result, the throughput capacity of thesensing system can easily be scaled based on the specificapplication-related throughput requirement for the sensing system. Sucha throughput-scalable sensing system does not require complex and costlyre-design of the sensor itself (e.g., redesign to add morephotosensitive elements in a single semiconductor die). Such athroughput-scalable sensing system also does not require a complexre-design or re-configuration of devices or sub-systems associated withthe sensors.

Furthermore, as described in more detail below, because multiplepackaged semiconductor dies in a throughput-scale sensing system arediced from a semiconductor wafer as a group, surfaces of the dies can beapproximately or substantially flat across multiple dies in a sensingsystem. This is because the surface of a semiconductor wafer istypically flat or substantially flat and because the multiple dies arediced from the wafer as a group. The approximately or substantially flatsurfaces across multiple wafer-level packaged semiconductor dies enableeasy disposing of an optical system and/or a sample channel acrossmultiple dies. This significantly reduces designing effort and solvesthe problem or difficulty of disposing an optical system and/or a samplechannel in a traditional wire-bonding based sensing system. As describedin more detail below, the group dicing technology described in thisdisclosure can further be combined with through-silicon via (TSV) andredistribution layer (RDL) technologies to provide signal redistributionfor reducing, avoiding, or replacing the need for wire bonding. The TSVpackaged semiconductor dies can maintain substantially flat surfacesacross multiple semiconductor dies for enabling easy sharing of a singleoptical waveguide and a single sample channel across multiple sensors ofa throughput-scalable sensing system.

Moreover, using the various embodiments of throughput-scalable sensingsystems described in this disclosure, many biological or chemicalsamples can be processed or analyzed in parallel or concurrently. Thisimproves the analysis throughput and speed over conventional analyticalsystems, which typically processes samples sequentially due to thethroughput capacity limitation. Further, the group dicing technologyenables a sensing system to be easily scaled or stacked up to provideparallel signal and data processing in a large-scale sensingapplication. The through-silicon via (TSV) and redistribution layer(RDL) technologies further eliminate the need for traditional wirebonding techniques for signal routing; and further enable theimplementation of a high throughput or a throughput-scalable sensingsystem. In some embodiments, the throughput-scalable sensing system canenable concurrent data processing in the order of, for example,millions, billions, or trillions of data units (e.g., data bitsrepresenting sensed photons). The various embodiments of thethroughput-scalable sensing systems can be used in or with differentapplications for analyzing biological or chemical samples including, forexample, nucleotide acid sequencing applications and polymerase chainreaction (PCR) applications.

FIG. 1 is a block diagram illustrating a top view and a cross-sectionalview a traditional image sensor system 100. System 100 includes an imagesensor 102 mounted on a frame 110 of an image sensor package. The imagesensor package can include, for example, a heat sink, pins, and epoxyplastic for providing protection to image sensor 102. Image sensor 102is packaged using a traditional wire bonding based method. For example,conventionally, a plurality of bonding pads 104 is disposed at the edgesof image sensor 102. Correspondingly, a plurality of bonding pads 108 isdisposed at frame 110 of the image sensor package. A plurality ofbonding wires 106 electrically couples pads 104 to corresponding pads108, thereby communicating electrical signals between image sensor 102and an external device (not shown).

Traditional image sensing system 100 has many limitations. As describedabove, the throughput of such as system is typically not easilyscalable. Scaling the throughput of such a system often requiresre-designing of image sensor 102 to incorporate more photosensitiveelements for satisfying the throughput requirement. Incorporating morephotosensitive elements inevitably requires increasing the physical chiparea of image sensor 102, re-designing the signal processing circuitry,re-designing the numbers and positions of bonding pads 104 and 108, andmany design-testing cycles. The scaling of such a traditional imagesensing system 100 thus requires significant redesign effort, extendedtime cycle to market, and increased cost. The scaling of such atraditional system becomes even more complex and costly if there aremultiple throughput requirements to be satisfied for different sensingsystems used for different applications.

Another limitation of traditional image sensing system 100 is specificto using system 100 for biological or chemical sample analysisapplications. This limitation relates to the flatness of the surface ofimage sensing system 100. In such applications, sample channels orsample containers are frequently disposed above image sensing system 100such that the light emitted by the samples can travel directly downwardto the image sensors without extra optical signal routing. As shown inthe cross-sectional view of image sensing system 100 in FIG. 1, bondingwires 106 are conventionally protected by epoxy material 112. Thus, dueto the using of bonding wires 106 and the epoxy 112, the surface ofimage sensing system 100 may not be flat or substantially flat.Disposing a sample channel or container above such an uneven surface mayrequire additional engineering efforts and may not be easily achieved.The task is further complicated if a sample channel or container is tobe shared across multiple image sensors 102. For example, additionalepoxy material may need to be disposed to the surface of image sensors102 to make the surface of system 100 flat. Or the samplechannel/container may need to be redesign/reconfigured to fit into theuneven surfaces of one or more image sensors 102. Both approaches imposechallenging design tasks. For instance, additional epoxy material mayinterfere with the light emitted from the sample disposed above imagesensor 102, by absorbing, diffracting, and/or reflecting the emittedlight. Thus, the additional epoxy material may render light detectionimpossible or impractical, or at least degrade the performance of imagesensing system 100. Redesigning the sample channel/container to fit intothe uneven surfaces of sensors 102 may sometimes be impractical or atleast increase the cost of system 100.

Unlike traditional image sensor system 100, various embodiments ofthroughput-scalable sensing systems are described in this disclosure.These throughput-scalable sensing systems are based on group dicing andbased on wafer-level packaging of multiple sensors disposed on multiplesemiconductor dies. The multiple semiconductor dies and a plurality ofdicing streets are arranged such that the multiple semiconductor diescan be diced from a single semiconductor wafer as a group. FIG. 2Aillustrates an exemplary wafer map 200 of such a semiconductor wafer. Asemiconductor wafer is a thin slice of semiconductor (e.g., Silicon)used for fabricating integrated circuits and/or other semiconductordevices such as sensors. Various types of sensors are described in thisdisclosure, including image sensors, chemically sensitive sensors,transmembrane pore based sensors, photon counting sensors, and quantaCMOS image sensors (QISs). These sensors are described in more detailbelow.

An image sensor is a sensor that detects photons, generate electricalsignals (also referred to as photoelectrons) based on the detectedphotons, and transmit the electrical signals for further signalprocessing. In an image sensing system, photons can be generated as aresult of fluorescence or chemiluminescence emissions from biological orchemical samples being analyzed. The photons are then collected anddetected by photosensitive elements (e.g., pixels) included in an imagesensor. Photosensitive elements can include, for example, photodiodes(e.g., silicon based photodiodes) for detecting photons and generatingelectrical signals based on detected photons. In some embodiments,photosensitive elements may also include amplifiers (e.g., avalancheamplification). The electrical signals generated by an image sensor canrepresent various photon information including the number of photonscollected, the position of photons, and/or the intensity of photons. Asdescribed in more detail below, an image sensor described in thisdisclosure is not limited to a sensor that transmits electrical signalsor information for generating an image. An image sensor used foranalyzing biological or chemical samples (e.g., nucleotide acidsequencing applications, polymerase chain reaction applications) caninclude sensors that detect photons and transmit electrical signals forany type of signal processing with or without generating an image.

With reference to FIG. 2A, wafer map 200 represents wafer-level packagedsemiconductor dies and their arrangements on a single semiconductorwafer. In some embodiments, as described in more detail below,wafer-level packaging of the semiconductor dies can include one or moreof forming through-silicon vias (TSV), depositing redistribution layers,depositing passivation layers, forming electrically-conductive spheres,and disposing solder mask layers. In this disclosure, wafer-levelpackaged semiconductor dies are sometimes also referred to as packagedsemiconductor dies or TSV-packaged semiconductor dies. In FIG. 2A, eachindividual block (e.g., block 202) shown on wafer map 200 can representa packaged semiconductor die of a semiconductor wafer. A semiconductordie is a unit or a single block of semiconductor material on whichintegrated circuits or other devices (e.g., sensors) are fabricated. Forexample, an image sensor having a plurality of photosensitive elements(e.g., pixels) can be fabricated on each semiconductor die representedby an individual block (e.g., block 202) shown on wafer map 200.Exemplary embodiments of such an image sensor is described in moredetail below.

In some embodiments, each image sensor can be fabricated on anindividual semiconductor die. An image sensor may have a pre-configuredor a pre-determined throughput capacity represented by a pixel arraysize. For example, an image senor may have a pixel array size of 8megapixels, 16 megapixels, 32 megapixels, etc. Typically, for a givensemiconductor process (e.g., a 45 nm CMOS image sensor process), alarger pixel array size requires more photosensitive elements such asmore photodiodes. As a result, an image sensor with higher throughputcapacity may require a larger physical area of a semiconductor die. Insome embodiments, rather than increasing the area of a singlesemiconductor die, a high throughput sensing system orthroughput-scalable sensing system can also be obtained based on groupdicing of multiple packaged semiconductor dies.

FIG. 2B illustrates an exemplary group dicing plan for dicing packagedsemiconductor dies from a semiconductor wafer as groups. As shown inFIG. 2B, multiple packaged semiconductor dies can be diced as a group,instead of individually, from the semiconductor wafer represented bywafer map 200. Dicing, sometimes also referred to as wafer dicing, is aprocess by which packaged semiconductor dies are separated from asemiconductor wafer or a wafer-level packaged semiconductor wafer. Adicing process may include scribing, breaking, mechanical sawing, and/orlaser cutting. Dicing is typically performed at or near dicing streetsbetween the packaged semiconductor dies. The dicing streets can be, forexample, 80 micrometers (um) wide.

In FIG. 2B, an exemplary dicing group is represented by a block 210illustrated on wafer map 200. The exemplary dicing group represented byblock 210 may include a plurality of individual packaged semiconductordies (e.g., 8, 16, 32, 64, etc.). An image sensor with a particularthroughput capacity may be fabricated on each packaged semiconductor diein the group. Therefore, block 210 on wafer map 200 can also represent agroup of image sensors disposed on the corresponding packagedsemiconductor dies. FIG. 2C illustrates a throughput-scalable imagesensing system obtained based on dicing multiple packaged semiconductordies as a group from a semiconductor wafer or a wafer-level packagedsemiconductor wafer. In FIG. 2C, an image sensor is pre-fabricated ordisposed on each packaged semiconductor die. For example, one imagesensor can be fabricated or disposed on packaged semiconductor die 222A.The image sensor disposed on packaged semiconductor die 222A mayinclude, for example, a plurality of photosensitive elements 224, aplurality of electrically-conductive layers (not shown in FIG. 2C), aplurality of electrically-conductive pads 226, and a semiconductor(e.g., silicon) substrate 228. The components and structure of exemplaryimage sensors are described in more detail below.

As shown in FIG. 2C, based on a group dicing plan, the packagedsemiconductor dies of the semiconductor wafer can be diced in groups.The example illustrated in FIG. 2C shows that a group of six packagedsemiconductor dies 222A-F are separated from the semiconductor wafer by,for example, laser cutting along the dicing streets 230A-D withoutseparating the packaged semiconductor dies 222A-F from one another.Dicing streets 230A-D represent the perimeter of the group of dies222A-F. And therefore, in group dicing, the laser cutting is performedalong the perimeter of the group of dies 222A-F, but not between thedies. Each of packaged semiconductor dies 222A-F can be pre-fabricatedor disposed with an image sensor having a particular throughout capacity(e.g., pixel array size). The six image sensors pre-fabricated ordisposed on packaged semiconductor dies 222A-F can thus form an imagesensing system 220 that has six-times throughput capacity than eachindividual image sensor. In general, if each image sensor in an imagesensing system (e.g., system 220) has a pixel array size of M megapixelsand there are N number of image sensors in the image sensing system, thetotal pixel array size of the image sensing system is then M×N. In theexample illustrated in FIG. 2C, if each image sensor disposed onsemiconductor dies 220A-F has a pixel array size of 64 megapixels, and agroup of six packaged semiconductor dies 220A-F form the image sensingsystem 220, image sensing system 220 can be scaled to have a pixel arraysize of 384 megapixels.

While FIG. 2C illustrates that image sensing system 220 include siximage sensors disposed on six packaged semiconductor dies 220A-F, it isappreciated that the number of image sensors in a particular imagesensing system can be determined or preconfigured to any desired numbersatisfying a throughput scaling requirement. For example, if aparticular image sensing system used for a nucleotide acid sequencingapplication requires a total pixel array size of 1000 megapixels (or 1Gigapixels), and if each image sensor has a pixel array size of 64megapixels, the number of image sensors required for such an imagesensing system would be about 16 (e.g., 1000/64). Correspondingly, 16packaged semiconductor dies can be diced from the semiconductor wafer asa group (i.e., without separating the 16 dies from one another).Accordingly, based on the throughput scaling requirement for the imagesensing system and based on a throughput capacity of each image sensor,the number of image sensors in the image sensing system can be readilydetermined. As a result, the throughput capacity of the image sensingsystem can easily be scalable based on requirements of the specificapplications (e.g., a DNA sequencing application, a PCR application) ofthe image sensing system. Such a throughput-scalable system does notrequire complex and costly re-design of the image sensor itself (e.g.,redesign to add more photosensitive elements in a single semiconductordie).

Further, a throughput-scalable image sensing system described in thisdisclosure also does not require a complex re-design or re-configurationof devices or sub-systems operating with the image sensors. FIG. 3 is ablock diagram illustrating a throughput-scalable sensing system 300.Sensing system 300 includes a plurality of sensors 320A-N. As describedbelow in more detail, sensors 320A-N can be image sensors, photondetection sensors, chemically sensitive sensors, transmembrane sensors,quanta CMOS image sensors (QISs) and/or other types of sensors used forperforming biological or chemical analysis. In a similar manner asdescribed above, sensors 320A-N can be pre-fabricated or disposed onpackaged semiconductor dies that are diced from a semiconductor wafer orwafer-level packaged semiconductor wafer as a group. In someembodiments, sensing system 300 can further include a fluidic reactionchannel 302, an optical system 304, and a signal and data processingsystem 330. In some embodiments, fluidic reaction channel 302, sometimesalso referred to as sample channel 302, is configured to exchange liquidreagent for analyzing biological or chemical samples. For example, in aDNA sequencing analysis, sequencing samples can be disposed insequencing reagents flowing through fluidic reaction channel 302. Insome embodiments, optical system 304 can be configured to performvarious functions including providing an excitation light (e.g., a laserlight), guiding or directing the excitation light to the samples underanalysis, and/or guiding or directing light emitted from the samples tosensors 320A-N (e.g., fluorescence or chemiluminescence light). Opticalsystem 304 can be optional depending on the specific type of sensorsand/or applications. In some embodiments, fluidic reaction channel 302and optical system 304 can be disposed across multiple image sensors320A-N in a throughput-scalable sensing system.

FIG. 4A is a cross-sectional view illustrating an exemplary fluidicreaction channel 302 and an optical waveguide 404 disposed across aplurality of sensors 320A-N in a throughput-scalable image sensingsystem 400A. In FIG. 4A, a plurality of sensors 320A-N is pre-fabricatedor disposed on a plurality of packaged semiconductor dies 422. Packagedsemiconductor dies 422 are diced from a single semiconductor wafer or awafer-level packaged semiconductor wafer as a group in a similar manneras described above. As shown in FIG. 4A, because packaged dies 422A-Nare diced from the semiconductor wafer or a packaged wafer as a group,the upper surfaces of packaged dies 422A-N can be approximately orsubstantially flat across packaged dies 422A-N. This is because thesurface of a semiconductor wafer or a wafer-level packaged wafer istypically flat or substantially flat. The approximately or substantiallyflat surfaces across multiple packaged semiconductor dies 422 enableeasy disposing of optical waveguide 404 and/or fluidic reaction channel302 across multiple dies. Optical system 404 can be part of opticalsystem 304 shown in FIG. 3. In some embodiments, as illustrated in FIG.4A, optical waveguide 404 can be disposed across multiple packagedsemiconductor dies 422A-N. Optical waveguide 404 can include anapproximately or substantially flat surface in contact with the uppersurfaces of plurality of packaged semiconductor dies 422A-N on whichimage sensors 320A-N are arranged or disposed. In turn, fluidic reactionchannel 302 can be disposed above optical waveguide 404. Fluidicreaction channel 302 can include an approximately or substantially flatsurface in contact with optical waveguide 404. As shown in FIG. 4A, insome embodiments, fluidic reaction channel 302 can include a fluid inlet408 and fluid outlet 410. Liquid reagent 414 can be directed to flowinto channel 302 from fluid inlet 408 and flow out of channel 302 fromfluid outlet 410.

In some embodiments, optical waveguide 404 is configured to deliver anexcitation light 406 along its longitudinal direction. For example,optical waveguide 404 may include one or more light-guiding layers(e.g., two cladding layers and an optical core layer) that directexcitation light 406 to illuminate biological or chemical samples 412disposed inside fluidic reaction channel 302. In some embodiments,fluidic reaction channel 302 can operate as a part of optical waveguide404 (e.g., operating as the optical core layer of optical waveguide404). Thus, in some embodiments, fluidic reaction channel 302 and one ormore light-guiding layers may be collectively referred to as opticalwaveguide 404. Excitation light 406 can be generated by a light source,which can include a laser or a light-emitting diode (LED) based lightsource that generates and emits excitation light 406. Excitation light406 can be, for example, a green light (e.g., a light having wavelengthin the range of about 520-560 nm) or any other desired light having adesired wavelength or wavelength range. The light source that generatesexcitation light 406 can be, for example, a diode laser or LED. Detailsof the optical waveguide 404, fluidic reaction channel 302, andexcitation light 406 are further described in International ApplicationNo. PCT/CN2019/087455, entitled “ANALYTICAL SYSTEM FOR MOLECULEDETECTION AND SENSING,” filed on May 17, 2019, the content of which isincorporated by reference in its entirety for all purposes.

As illustrated in FIG. 4A, because packaged semiconductor dies 422A-N(on which image sensors 320A-N are arranged) are diced as a group from asame wafer-level packaged semiconductor wafer, the surfaces of packagedsemiconductor dies 422A-N are approximately or substantially flat. Theflatness of the surfaces across the packaged semiconductor dies dicedfrom a same semiconductor wafer as a group enables easy sharing ordisposing of a single optical waveguide (e.g., waveguide 404) and asingle fluidic reaction channel (e.g., channel 302) across multiplesensors 320A-N of a throughput-scalable sensing system. Such a sharingmay not be practical or possible in traditional sensing systems. Asdescribed above, a traditional image sensor (e.g., image sensor 102shown in FIG. 1) is packaged using a wire bonding based method. As aresult, bonding wires and epoxy for protecting the bonding wires mayrender the surface of the image sensor uneven. The uneven surface makesit difficult, impractical, or impossible to share optical waveguide andfluidic reaction channel across multiple image sensors. The unevensurface of an image sensor may also negatively impact the performance ofthe fluidic reaction channel, because some portions of the channel mayneed to be curved/shaped due to the uneven surface of the image sensor.A curved fluidic reaction channel restricts or limits the fluid flowinside the channel. As described in more detail below, the group dicingtechnology described in this disclosure can further be combined withthrough-silicon via (TSV) and redistribution layer (RDL) technologies toprovide signal redistribution for reducing, avoiding, or replacing theneed for wire bonding. As described in more detail below, the TSVpackaged semiconductor dies can maintain approximately or substantiallyflat surfaces across multiple semiconductor dies for enabling sharing ordisposing of a single optical waveguide (e.g., waveguide 404) and asingle fluidic reaction channel (e.g., channel 302) across multiplesensors 320A-N of a throughput-scalable sensing system.

With reference to FIG. 4A, in some embodiments, samples 412A-N (e.g.,clusters of biological or chemical samples) can be disposed at positionscorresponding to sensors 320A-N, respectively. For example, sample 412Ais disposed above sensor 320A and is physically aligned with sensor320A; sample 412B is disposed above sensor 320B and is physicallyaligned with sensor 320B; and so forth. The light emitted from samples412A-N disposed in fluidic reaction channel 302 can be detected bycorresponding sensors 320A-N. Because samples 412A-N and correspondingsensors 320A-N are aligned with each other, respectively, the lightcollection efficiency of sensors 320A-N can be improved or maximized.Based on the group dicing technology described above, multiple sensors320A-N can form a throughput-scalable sensing system, effectivelyincreasing the throughput capacity of the sensing system. While FIG. 4Aillustrates that sensors 320A-N are arranged as a one-dimensional array,it is appreciated that they can be arranged as a two-dimensional arrayof any size (e.g., 3×3, 6×6, 10×10, etc.).

In some embodiments, excitation light 406 may not be delivered usingoptical waveguide 404 as illustrated in FIG. 4A. Instead, excitationlight 406 can be guided to directly illuminate samples 412A-N, asillustrated in FIG. 4B. FIG. 4B is a cross-sectional view illustratingan exemplary fluidic reaction channel 302 with direct illuminationacross a plurality of sensors 320A-N in a throughput-scalable imagesensing system 400B. System 400B can be configured to be substantiallythe same as system 400A except that system 400B does not include anoptical waveguide for directing excitation light 406. For example, toilluminate samples 412A-N in system 400B without using an opticalwaveguide, excitation light 406 can be guided to provide illumination tosamples 412A-N from above fluidic reaction channel 302, as shown in FIG.4B. Excitation light 406 can be guided using, for example, focused lens,filters, and/or any other desired optical elements.

With reference back to FIG. 3, based on the detection of light emittedfrom samples disposed in fluidic reaction channel 302, multiple sensors320A-N can generate and transmit electrical signals to a signal and dataprocessing system 330 for further signal and data processing. As aresult, data generated for samples disposed in the fluidic reactionchannel 302 can be processed in parallel in a large scale. Datagenerated for many samples can be processed concurrently, insubstantially the same time, or in a short time period. The capabilityof concurrent or parallel processing of data improves the testingthroughput and speed over conventional analytical systems. Further, asdiscussed above, the group dicing technology enables the image sensingsystem to be easily scaled or stacked up to provide parallel signal anddata processing in a large-scale image sensing application (e.g., 100meg-1 giga imaging application). For example, 20 image sensors canprovide 20 times more image sensing area due to the increased number ofphotosensitive elements (e.g., pixels) included in the 20 image sensors.If each image sensor has 100 meg pixel array size, 20 image sensorswould have 2000 meg or 2 giga pixels, thereby greatly improving thethroughput capacity and analysis speed. Further, such a scaling of thesensing system does not require complex system re-design associated withtraditional methods for providing a high-throughput sensing system. Forexample, in some embodiments, each sensor 320A-N can have its ownamplifier, filter, and/or associated shutter and readout circuity, andcan be electrically isolated from other sensors. Thus, the re-designeffort for sensors 320A-N and their associated signal processingcircuitry can be significantly reduced or minimized.

A throughput-scalable image sensing system obtained based on the groupdicing technology described in this disclosure can be particularlyuseful for many applications involving photon counting. Suchapplications include, for example, analysis of biological or chemicalsamples using light emitted from the samples. For example, based on thephotons collected and detected by multiple image sensors in ahigh-throughput image sensing system, multiple nucleotide acidsequencing processes can be concurrently performed. Further, for sampleanalysis applications such as nucleotide acid sequencing applications,an image sensing system (e.g., system 300) is required to perform photoncounting and generate an image based on the results of photon counting.The image thus generated may represent certain information (e.g., photonintensity) associated with the sample analysis. But such an image maynot be required to be a continuous image or may be allowed to have gapsbetween different portions of the image. A sensing system obtained basedon group dicing of multiple dies may generate image with gaps.

With reference to back to FIG. 2C, multiple image sensors are disposedon packaged semiconductor dies 222A-F. As illustrated in FIG. 2C,photosensitive elements of the multiple image sensors are not physicallycontinuous or connected with one another. For example, photosensitiveelements 224 of the image sensor disposed on die 222A are physicallyseparated from photosensitive elements 234 of the image sensor disposedon die 222B. Between the photosensitive elements of different imagesensors, other device structures or components (e.g., pads 226) anddicing streets (e.g., dicing street 235 between dies 222A and 222B) mayexist. As a result, an image generated by multiple image sensorsdisposed on separate packaged semiconductor dies 222A-F may not becontinues or may have one or more image gaps between different portionsof the image. Image gaps can be blank or dark areas between differentportions of an image due to the lack of photon sensing between thephotosensitive elements. Such image gaps may not be acceptable forcertain imaging applications that require a continuous image to beprovided. Such applications may include, for example, traditionalphoto-capturing applications (e.g., taking portrait photos, picturing areal-world object, etc.), surveillance camera applications, or securitymonitoring applications.

Further, for those applications in which image gaps are not acceptableor tolerable, if a raw image generated by multiple image sensors is notcontinues or has image gaps, significant image processing efforts may berequired to remove or mitigate the image gaps. For example,post-capturing image processing may be applied to stitch portions of theimages together to provide an acceptable image without image gaps. Thus,an image sensing system with multiple image sensors that havediscretely-positioned photosensitive elements (e.g., elements that arenot physically continuous or connected with one another) may not beeasily designed or implemented for certain imaging applications. Incontrast, such an imaging system may not have or may have minimum impacton performance of a biological or chemical sample analysis applicationsuch as a nucleotide acid sequencing application. For many biological orchemical sample analysis applications, the image sensors are used tocount photons emitted from the samples and generate an image base on thephotons. The image can be allowed to have image gaps, because theanalysis results can be derived based on the information related tophoton detections (e.g., the intensity of photons, position of photons,pattern of photons, etc.). The derivation of the analysis results doesnot require the image to be continuous or without image gaps. Therefore,a high-throughput image sensing system including multiple image sensorsobtained based on group dicing technologies can be readily used for manybiological or chemical sample analysis application or any other photoncounting based applications, without requiring any mitigation effort toremove the image gaps caused by the discretely-positioned photosensitiveelements.

With reference back to FIG. 3, sensors 320A-N can be different types ofimage sensors, such as back-side illumination based image sensors orfront-side illumination based sensors. As described above, because imagesensors necessarily detect photons, they are sometimes also referred toas, or used as, photon detection sensors, photon counting sensors, orphotoelectron counting sensors. In addition, while the above descriptionwith respect to FIG. 3 use image sensors as examples, sensors 320A-N canalso be other type of sensors such as chemically sensitive sensors,transmembrane pores based sensors, photon detection sensors, photoncounting sensors, and/or quanta CMOS image sensors (QIS). These types ofsensors are each described in more detail below. Further, it isappreciated that blocks in FIG. 3 are for illustration purposes and notfor defining the boundary of devices. For example, one or morecomponents, devices, or subsystems of signal and data processing system330 may be integrated or combined with sensors 320A-N, and vice versa.

FIG. 5A illustrates an embodiment of an image sensing system 500A with across-sectional view of an embodiment of a TSV packaged BSI-based imagesensor 520A. Image sensor 520A can be one embodiment of one or more ofsensors 320A-N as shown in FIG. 3. As shown in FIG. 5A, image sensor520A includes a semiconductor substrate 502, on which integratedcircuits or devices can be fabricated or disposed. Semiconductorsubstrate 502 can be, for example, a silicon-based substrate forenabling the integrated circuits or devices to be fabricated usingcomplementary metal-oxide semiconductor (CMOS) processes. Image sensor520A can further include a photon detection layer 504, one or moreconductive layers 506, one or more dielectric layers 507, and a filter508. In some embodiments, photon detection layer 504 includes aplurality of photosensitive elements 505A-N (collectively asphotosensitive elements 505). Each photosensitive element 505 may alsobe referred to as a pixel. And the plurality of photosensitive elements505 may form a pixel array. In some embodiments, photosensitive elements505 can include, for example, photodiodes (e.g., silicon-basedphotodiodes) and amplifiers, for detecting photons and generatingelectrical signals (e.g., photoelectrons) based on detected photons.Similar to those described above with respect to FIGS. 3 and 4A, afluidic reaction channel (e.g., channel 302) and an optical system(e.g., system 304) may be disposed above image sensor 520A. To obtainfluorescence light, for example, the optical system can be an opticalwaveguide that delivers an excitation light to the samples disposed inthe fluidic reaction channel. In some embodiments, the optical systemdoes not include an optical waveguide. Instead, the optical system caninclude focus lens, optical filters, and/or any other desired opticalelements for providing illumination from above fluidic reaction channel302 (similar to that shown in FIG. 4B). The light emitted as a result ofanalyzing the biological or chemical samples disposed in the fluidicreaction channel may be detected by the photosensitive elements 505 ofphoton detection layer 504. Based on detected photons, thephotosensitive elements 505 of the photon detection layer 504 generateelectrical signals (photoelectrons). While FIG. 5A illustrates one imagesensor 520A, it is appreciated that multiple image sensors can beincluded in image sensing system 500A. The multiple image sensors can beconfigured similar to that shown in FIG. 4A or 4B.

With reference to FIG. 5A, image sensor 520A illustrates an embodimentof a back-side illumination (BSI) based image sensor structure. In aBSI-based image sensor, the photon detection layer 504 are disposedcloser to the samples under analysis than to the conductive layers 506.As shown in FIG. 5A, fluidic reaction channel 302, or a portion thereof,can be disposed above photon detection layer 504 (and above the filter508, optional passivation layer 510, and/or optical system 304).Therefore, the biological or chemical samples disposed inside fluidicreaction channel 302 are positioned further to conductive layers 506than photon detection layer 504 in the vertical direction. Thus, in aBSI-based image sensor, the light emitted from the samples travels tophoton detection layer 504 without having to traveling through multipleconductive layers 506. As a result, the distance of light traveling inan BSI-based image sensor is shorter compared to that of an FSI-basedimage sensor. BSI-based image sensors can thus greatly reduce the signalloss and cross talk due the shorter distance that the light emitted fromthe samples has to travel. The shorter distance of light traveling in anBSI-based image sensor also eliminates or reduces the need foradditional fluorescence or chemiluminescence light collection optics.Further, by eliminating the multiple conductive layers in the lightpath, a substantial or entire area of photosensitive elements 505 ofphoton detection layer 504 can have access or be sensitive to the lightemitted from the samples. A BSI-based image sensor can thus reduce lightabsorption compared to an FSI-based image sensor. In some embodiments,the quantum efficiency of a BSI-based image sensor can be improved(e.g., by 80-90%) comparing to an FSI-based image sensor. Reducingsignal loss and having higher quantum efficiency in turn improves imagequality and resolution, and reduces the need for a highly-sensitiveimage sensor.

As illustrated in FIG. 5A, the electrical signals, or photoelectrons,generated by photon detection layer 504 can be collected and conductedby the plurality of conductive layers 506. Conductive layers 506 caninclude one or more layers of metal layers and vias interconnecting themetal layers. Conductive layers 506 are configured to electricallycouple the photosensitive elements 505 to one or moreelectrically-conductive pads 514. For example, conductive layers 506 cantransmit the electrical signals generated by the photosensitive elements505 of photon detection layer 504 to one or more electrically-conductivepads 514. In some embodiments, the electrical signals generated by thephotosensitive elements 505 may be further processed before they aretransmitted to electrically-conductive pads 514. For example, conductivelayers 506 can be part of a signal amplification, readout, and/orconversion circuitry (not shown). These signal amplification, readout,and/or conversion circuitry are collectively referred to as the signalprocessing circuitry, which can be part of signal and data processingsystem 330 shown in FIG. 3. In some embodiments, the signal processingcircuitry can include, for example, avalanche amplification circuitry,an in-pixel readout circuit, a correlated double sampling (CDS) circuit,a sense amplifier, and/or an analog-to-digital (ADC) conversion circuit.In some embodiments, one or more of the signal amplification, readout,and/or conversion circuitry are implemented for each photosensitiveelement 505 (e.g., each pixel) or shared across multiple photosensitiveelements 505 (e.g., shared by each readout cluster) of photon detectionlayer 504. For instance, each image sensor fabricated or disposed on asemiconductor die can have its own signal processing circuitry, whichprocesses the electrical signals generated by the particular imagesensor independently from other image sensors. This enables parallel orconcurrent processing of electrical signals of multiple image sensors,thereby improving the overall throughput of the image sensing system.

In some embodiments, one or more of the signal amplification, readout,and/or conversion circuitry can be implemented in the same semiconductordie or wafer as the photosensitive elements 505. In some embodiments,one or more of the signal amplification, readout, and/or conversioncircuitry can be implemented in a different semiconductor die or waferthan that for the photosensitive elements 505. For example, as describedin more detail below, a first semiconductor wafer (also referred to as adetection wafer) can be configured to implemented photosensitiveelements 505 (e.g., photodiodes) and a second semiconductor wafer (alsoreferred to as an ASIC wafer) can be configured to implement a signalprocessing system including the readout circuitry. Electrical couplingbetween the two semiconductor wafers can use, for example, wafer-levelpackaging techniques such as wafer bonding and TSV techniques. As aresult, the detection wafer can include many more photosensitiveelements due to the extra wafer area made available by disposing signalprocessing circuitry in another wafer, thereby further improvingthroughput of the image sensing system.

With reference to FIG. 5A, image sensor 520A can further include afilter 508 and an optional passivation layer 510. Filter 508 can bedisposed between optical system 304 (e.g., an optical waveguide) andphoton detection layer 504. In some embodiments, filter 508 can beconfigured to remove a substantial portion of light having a firstwavelength range. The first wavelength range is different from one ormore wavelength ranges associated with the light emitted as a result ofanalyzing the biological or chemical samples disposed in fluidicreaction channel 302. For example, filter 508 can include a coatingdeposited on photon detection layer 504 for removing a substantialportion of scattered or leakage light in the wavelength range of theexcitation light (e.g., green light), while allowing a substantialportion of the light emitted from the samples to pass (e.g., yellowlight and/or red light). Thus, filter 508 can improve thesignal-to-noise ratio by allowing desired light signals to reach photondetection layer 504 while blocking undesired light signals (e.g.,background noise and/or excitation light leakage). In some embodiments,filter 508 can be a different type of coating deposited on photondetection layer 504 such that a plurality of filter cells of the filter508 is interleaved (e.g., forming a chessboard pattern separatingdifferent types of cells by a grid structure) to reduce crosstalkbetween adjacent photosensitive elements 505 (e.g., adjacent pixels) ofthe photon detection layer 504. Crosstalk is often undesired because thelight emitted from one sample can be affected by the light emitted fromanother sample, resulting in signal distortion for some photosensitiveelements 505 (e.g., pixels) of an image sensor. Filter 508 can remove,for example, a substantial portion of all lights (e.g., absorb lights inall wavelength ranges or any desired wavelength ranges). Thus, byinterleaving filter cells of filter 508, crosstalk can be reduced oreliminated.

In some embodiments, image sensor 520A can include a passivation layer510. In some embodiments, passivation layer 510 can be a polymer coatingwith low refractive index or a silicon dioxide layer. Passivation layer510 can effectively separate fluidic reaction channel 302 from otherlayers or devices of image sensor 500, such that other layers or devicesare protected from liquid and/or mechanical damage. For example,passivation layer 510 can protect the photosensitive elements 505 ofphoton detection layer 504, conductive layers 506, and/or signalprocessing circuitry (not shown) from liquid and/or mechanical damage.

As described above, by including multiple image sensors disposed onpackaged semiconductor dies that are obtained based on the group dicingtechnology, a throughput-scalable image sensing system can be provided.Such a system can be scaled to have high throughput (e.g., millions orbillions of image pixels). Such a high-throughput system also does notrequire traditional wire bonding techniques to transmit electricalsignals from the image sensors to external circuitry. Wire bondingtechniques may be associated with many disadvantages or drawbacks asdescribed above, and in particular, may impose difficulties in a highthroughput image sensing system that has large or high-density pixelarrays. In some embodiments, through-silicon vias (TSV) andredistribution layer (RDL) routing technologies can be used incombination with the group dicing technology to obtain a high-throughputimage sensing system. In FIG. 5A, the plurality of conductive layers 506electrically couples the photosensitive elements 505 of photon detectionlayer 504 to one or more electrically-conductive pads 514. For example,a top metal layer (e.g. metal layer 4) may be physically routed to pads514. Thus, the electrical signals generated by the photosensitiveelements 505 of photon detection layer 504, or processed signals (e.g.,amplified, sensed, converted signals), can be transmitted to pads 514.

As shown in FIG. 5A, pads 514 can be disposed at a surface 524 of thesemiconductor die on which image sensor 520A is fabricated or disposed.Surface 524 can be a surface of the semiconductor die with or withoutpassivation layer 510. In some embodiments, surface 524 can be a backsurface of a die (e.g., the surface at or near which no conductivelayers for signal routing is disposed), or a back surface of a die withreduced thickness (e.g., a thinned back surface of a semiconductor die).As illustrated, fluidic reaction channel 302 (or a portion thereof) andoptical system 304 (or a portion thereof) may be disposed above imagesensor 520A and in particular on surface 524 (or on passivation layer510). As described above, fluidic reaction channel 302 and opticalsystem 304 can be disposed across multiple semiconductor dies on whichimage sensors are fabricated or disposed. Therefore, couplingelectrically-conductive pads 514 to external circuitry using bondingwires may be difficult or impractical because the bonding wires wouldinterfere with the disposing of fluidic reaction channel 302 and/oroptical system 304.

In some embodiments, image sensor 520A can include one or morethrough-hole vias 512. Through-hole vias 512 may be through-silicon viasformed by anisotropic or directional etching (e.g., dry etching) ofsemiconductor substrate 502 near the areas of pads 514. Through-holevias 512 can form a channel or pipe that cuts through the a portion orentire thickness of semiconductor substrate 502 at or near the areas ofpads 514. Subsequently, a redistribution layer (RDL) 516 can bedeposited for signal re-routing. An RDL is an extra conductive layer(e.g., metal layer) that renders input/output pads (e.g., pads 514) ofan integrated circuit or device available in other locations. In someembodiments as shown in FIG. 5A, RDL 516 can include conductors at leastpartially enclosed by through-hole vias 512. The conductors of RDL 516further extends from pad 514 to one or more electrically-conductivespheres 518. Spheres 518 can be, for example, solder balls. RDL 516electrically couples pads 514 to spheres 518, thereby rerouting theelectrical signals from pads 514 to spheres 518. Spheres 518 can bedisposed at a surface 526. In some embodiments, surface 526 can be aprocessed substrate surface (e.g., a thinned surface) of anothersemiconductor die or wafer. For example, as described in more detailbelow, a carrier wafer can be bonded to the wafer on which the imagesensors are disposed or fabricated. The substrate of the carrier wafercan be thinned. Substrate 501 shown in FIG. 5A illustrates such athinned portion of the carrier wafer. And thus surface 526 is a thinnedsurface of substrate 501 of the carrier wafer. In some embodiments, nocarrier wafer is used and therefore surface 526 can be, for example, afront surface of a semiconductor die (e.g., the surface at or near whichconductive layers 506 for routing signals are disposed).

As illustrated in FIG. 5A, using through-hole vias 512 and RDL 516,electrical signals can be re-routed from first surface 524 of thesemiconductor die to second surface 526. Further signal routings orcoupling can thus be rendered at second surface 526 usingelectrically-conductive spheres 518. For instance, wafer level packagingor bonding can be performed such that a first wafer (e.g., a detectionwafer) comprising multiple image sensors can be electrically coupled toa second wafer (e.g., a signal processing wafer or ASIC wafer) using theelectrically-conductive spheres 518. The TSV and RDL technologies thuseliminate the need for traditional wire bonding techniques for routingsignals, and can further enable the implementation of a high throughputor throughput-scalable image sensing system.

With reference to FIG. 5A, in some embodiments, a solder mask layer 522can be disposed between two neighboring spheres 518. Solder mask layer522 can be disposed in contact with at least a portion of semiconductorsubstrate 501 and in contact with at least a portion of RDL 516. Soldermask layer 522 can be, for example, a layer of polymer or epoxy that isapplied to a surface to protect again oxidation of an underlyingconductive layer (e.g., RDL 516) or to prevent solder bridges fromforming between closely spaced electrically-conductive spheres (e.g.,two neighboring spheres 518).

FIG. 5B illustrates an exemplary image sensing system 500B with across-sectional view of another embodiment of a TSV packaged BSI-basedimage sensor 520B. With reference to FIG. 5B, similar to image sensor520A shown in FIG. 5A, image sensor 520B is a BSI-based image sensorincluding a semiconductor substrate 532, a photon detection layer 534including a plurality of photosensitive elements 535, one or moreconductive layers 536, a filter 538, and two passivation layers 539A-B.These components or layers of image sensor 520B can be the same orsubstantially the same as semiconductor substrate 502, photon detectionlayer 504, conductive layers 506, filter 508, and passivation layer 510of image sensor 520A, respectively, and therefore are not repeatedlydescribed.

In some embodiments, in addition to image sensor 520B, image sensingsystem 500B illustrated in FIG. 5B can further include a firstconductive layer 542, a second conductive layer 544, a plurality ofmicrolenses 540, and a planarization layer 546. First conductive layer542, microlenses 540, and second conductive layer 544 can implementoptical system 304 in FIG. 3. First conductive layer 542 and a secondconductive layer 544 can include metal layers. Microlenses 540 caninclude one or more optical elements such as lens, mirrors, lens-likestructures, or the like. Microlenses 540 can be made of glass, polymers,plastics, or the like. As illustrated in FIG. 5B, passivation layer 539Ais disposed above and in contact with filter 538. First conductive layer542 is disposed above and in contact with passivation layer 539A. Firstconductive layer 542 can be substantially flat. Second conductive layer544 can be disposed above the first conductive layer 544 and theplurality of microlenses 540. In some embodiments, second conductivelayer 544 can have a curved shape as illustrated in FIG. 5B. In someembodiments, image sensor 520B can include one or more openings 548etched through first conductive layer 542, second conductive layer 544,the plurality of microlenses 540, and planarization layer 546. Thus,neighboring microlenses of the plurality of microlenses 540 areseparated by one of openings 548. Openings 548 can be configured toreceive biological or chemical samples 412 and liquid reagents. Thus,openings 548 can implement, be associated with, at least a portion offluidic reaction channel 302 of FIG. 3.

In some embodiments, excitation light 406 can be guided or directed tosamples disposed in openings 548. As a result, fluorescence light can begenerated and emitted from the samples 412. In some embodiments, noexcitation light is used. Samples disposed in openings 548 may emitchemiluminescence light without external excitation light. Thefluorescence light and chemiluminescence light are collectively referredto as light emitted from samples 412. In some embodiments, firstconductive layer 542, microlenses 540, and second conductive layer 544can focus or direct light emitted from samples 412 to filter 538 and theunderneath photosensitive elements 535 in photon detection layer 534.For example, light emitted from the samples 412 can pass throughmicrolenses 540 and focused/collected by microlenses 540. The light thatpasses through microlenses 540 can be reflected by second conductivelayer 544, because layer 544 has a curved shape configured to reflectlight. Second conductive layer 544 can also block or partially blockexcitation light 546, thereby reducing the amount of undesired lighttraveling to filter 538.

In some embodiments, the light emitted from the samples 412 may alsopass through microlenses 540 and be reflected by first conductive layer542, and subsequently refocused or reflected (e.g., by second conductivelayer 544) toward filter 508 and the underneath photosensitive elements535 of photon detection layer 504. As a result, using first conductivelayer 542, microlenses 540, and second conductive layer 544, thecollection efficiency of the light emitted from the samples 412 can beimproved. The requirements for a high performance filter 538 and highefficiency photon detection layer 534 can therefore be reduced oralleviated. For example, the intensity of chemiluminescence light insome biological or chemical analysis applications can be low, andtherefore an improved light collection efficiency may be required toprovide a good analysis result. In some embodiments, as illustrated inFIG. 5B, filter 538 can have multiple filter cells 538A disposed atpositions corresponding to openings 548; and the underneathphotosensitive elements 535 of photon detection layer 534 can be furtherdisposed at areas corresponding to filter cells 538A. Therefore, therespective openings 548, filter cells 538A, and photosensitive elements535 of photon detection layer 534 can be geometrically aligned toimprove or maximize the detection of the emitted light from samples 412.In some embodiments, in filter 538, filter cells 538A are interleavedwith metal 538B for further reflection or focus of emitted light towardthe underneath photosensitive elements 535 of photon detection layer534. In some embodiments, one or more optical elements or portions ofmicrolenses 540 may be removed for disposing samples 412 in openings548. The remaining optical elements of microlenses 540 can collect,refocus, and/or reflect emitted signals to improve collectionefficiency. More details of the structure, operation, and fabricationsteps of image sensor 520B can be found in International Application No.PCT/US2017/059908, entitled “BIOSENSORS FOR BIOLOGICAL OR CHEMICALANALYSIS AND METHODS OF MANUFACTURING THE SAME,” filed on Nov. 3, 2017,the content of which is incorporated by reference in its entirety.

Similar to those described in FIG. 5A, TSV packaging and RDLtechnologies can be applied to image sensor 520B to provide ahigh-throughput or throughput-scalable image sensing system. Forexample, as shown in FIG. 5B, RDL 516 can be disposed to electricallycouple pads 514 and spheres 518, thereby re-routing signals from pads514 to spheres 518. Spheres 518 can be further electrically coupled toexternal signal processing circuitry. Further, group dicing technologycan also be applied to obtain a throughput-scalable image sensing systembased on image sensor 520B, such that multiple image sensors 520B aredisposed on packaged semiconductor dies diced from a wafer as a group.The details of TSV packaging, RDL routing, and group dicing technologiescan be applied in a similar manner as described above, and are thus notrepeatedly described here. While FIG. 5B illustrates one image sensor520B, it is appreciated that multiple image sensors can be included inimage sensing system 500B. The multiple image sensors can be configuredsimilar to that shown in FIG. 4A or 4B.

FIG. 5C illustrates an exemplary image sensing system 500C with across-sectional view of an embodiment of a front-side illumination (FSI)based image sensor 520C with TSV packaging. As described above, in aBSI-based image sensor, the light emitted from the samples travels tothe photon detection layer without having to traveling through thedistance of multiple conductive layers. In contrast, in an FSI-basedimage sensor, light emitted from samples disposed in a fluidic reactionchannel typically travels through the distance of multiple conductivelayers before it can reach the photon detection layer. Therefore,certain structural configurations may be required to reduce the loss ofemitted light before it reaches the photon detection layer. Asillustrated in FIG. 5C, similar to image sensor 520A shown in FIG. 5A,image sensor 520C includes a semiconductor substrate 552, a photondetection layer 554, one or more conductive layers 556, and apassivation layer 559. These components or layers of image sensor 520Ccan be the same or substantially the same as semiconductor substrate502, photon detection layer 504, the plurality of conductive layers 506,and passivation layer 510 of image sensor 520A, respectively, andtherefore are not repeatedly described.

With reference to FIG. 5C, in some embodiments, excitation light 406 canbe directed or guided to samples disposed in fluidic reaction channel302 from the top (e.g., perpendicular to the longitudinal direction offluidic reaction channel 302) as shown in FIG. 5C. As a result of theexcitation, fluorescence light is emitted from the samples disposed influidic reaction channel 302. In some embodiments, image sensor 520Cfurther includes a filter 558 as shown in FIG. 5C. Filter 558 caninclude materials for removing a substantial portion of light having afirst wavelength range. The first wavelength range is different from oneor more wavelength ranges associated with the light emitted as a resultof analyzing the biological or chemical samples disposed in fluidicreaction channel 302. For example, filter 558 can includelight-absorbing material for removing a substantial portion of scatteredor leakage light in the wavelength range of excitation light 406 (e.g.,green light); while allowing a substantial portion of the light emittedfrom the samples to pass (e.g., yellow light and/or red light).

In some embodiments, in addition to preventing excitation light 406, ora substantial portion thereof, from reaching photosensitive elements555A-N (collectively as photosensitive elements 555) of photon detectionlayer 554, filter 558 can be configured to direct or guide light emittedfrom samples disposed in fluidic reaction channel 302 to photosensitiveelements 555 of photon detection layer 554. As described above, for anFSI-based image sensor, the distance that the emitted light travels istypically longer than that in a BSI-based image sensor, due to thethickness of the conductive layers 556 (and one or more dielectriclayers 557 associated with the conductive layers 556). Filter 558 canthus be configured to reduce or minimize the loss of emitted light alongthe path to the photosensitive elements 555 of photon detection layer554. As one example, filter 558 can include a flat portion 558A and oneor more filter protrusions 558B. Filter protrusions 558B are configuredto provide filter channels directing at least a portion of the lightemitted as a result of analyzing the biological or chemical samples tothe plurality of photosensitive elements 555 of photon detection layer554. In FIG. 5C, filter protrusions 558B are configured such that theirtop portions (e.g., the portions that are closer to fluidic reactionchannel 302) are wider than the bottom portions (e.g., the portions thatare further away from fluidic reaction channel 302). As a result, widertop portions of filter protrusions 558B can improve or maximize thecollection efficiency for collecting the light emitted from samplesdisposed in fluidic reaction channel 302. And narrower bottom portionsof filter protrusions 558B can be positioned corresponding to thepositions of photosensitive elements 555 of photon detection layer 554,thereby improving or maximizing the detection efficiency of thephotosensitive elements 555.

In some embodiments, filter protrusions 558B can include walls 558C incontact with semiconductor substrate 552, conductive layers 556, and/ordielectric layers 557. Walls 558C of filter protrusion 558B can include,for example, reflective coatings for reflecting or directing emittedlight toward photosensitive elements 555 of photon detection layer 554.The reflective coatings can include, for example, metal coatings oroptical coatings. In some embodiments, one or more conductive layers 556can be disposed or distributed around filter protrusions 558B to reduceor minimize crosstalk due to the distance that the emitted light has totravel in FSI-based image sensor 520C. Crosstalk may occur betweenadjacent photosensitive elements 555 (e.g., adjacent pixels) of thephoton detection layer 554. Crosstalk is often undesired because thelight emitted from one sample can be affected by the light emitted fromanother sample, resulting in signal distortion for some photosensitiveelements 555 (e.g., pixels) of an image sensor. In some embodiments, theportions of conductive layers 556 distributed near or around filterprotrusion 558B can remove, for example, a substantial portion of alllights (e.g., absorb lights in all wavelength ranges or any desiredwavelength ranges). Thus, crosstalk can be reduced or eliminated. Moredetails of the structure, operation, and fabrication steps of anFSI-based image sensor can be found in U.S. Patent ApplicationPublication No. US2016/0356715, entitled “BIOSENSORS FOR BIOLOGICAL ORCHEMICAL ANALYSIS AND METHODS OF MANUFACTURING THE SAME,” filed on Jun.7, 2016, the content of which is incorporated by reference in itsentirety for all purposes.

Similar to those described in FIG. 5A, TSV packaging and RDLtechnologies can be applied to image sensor 520C to provide ahigh-throughput or throughput-scalable image sensing system. Forexample, as shown in FIG. 5C, RDL 516 can be disposed to electricallycouple pads 514 and spheres 518, thereby re-routing signals from pads514 to spheres 518. Spheres 518 can be further electrically coupled toexternal signal processing circuitry. Because FIG. 5C illustrates anFSI-based image sensor 520C, pads 514 are disposed at or near a frontsurface of a packaged semiconductor die (e.g., the surface at or nearwhich conductive metal layers for routing signals are disposed). Andspheres 518 are disposed at or near a back surface of a packagedsemiconductor die (e.g., the surface at or near which no conductivelayers for routing signals is disposed or a surface). Thus, the surfacesfor disposing pads 516 and spheres 518 in an FSI-based image sensor arethe opposite to those in an BSI-based image sensor. Further, groupdicing technology can also be applied to obtain a throughput-scalableimage sensing system based on image sensor 520C, such that multipleimage sensors 520C are disposed on packaged semiconductor dies dicedfrom a wafer as a group. The details of TSV packaging, RDL routing, andgroup dicing technologies can be applied in a similar manner asdescribed above, and are thus not repeatedly described here. While FIG.5C illustrates one image sensor 520C, it is appreciated that multipleimage sensors can be included in image sensing system 500C. The multipleimage sensors can be configured similar to that shown in FIG. 4A or 4B.

With reference back to FIG. 3, in the above description, while sensors320A-N can be implemented as image sensors (e.g., image sensors 520A-C),they can also be implemented as other types of sensors such as achemically sensitive sensor. Thus, system 300 can be adapted to achemical sensing system rather than an image sensing system. It isappreciated one or more blocks/components shown in FIG. 3 may not beincluded in a chemical sensing system; and additional blocks/componentsmay be added to a chemical sensing system. FIG. 5D illustrates anexemplary chemical sensing system 500D with a cross-sectional view of anembodiment of a TSV packaged chemically sensitive sensor 520D.

A chemically sensitive sensor can measure certain concentrations orother chemical properties of chemical ingredients of biological orchemical samples. A chemically sensitive sensor 520D can include, forexample, an ion-sensitive field effect transistor (ISFET) based sensor.An ISFET-based sensor can measure ion concertation for samples (e.g.,samples 412 such as beads) disposed in liquid reagents. When the ionconcentration (e.g., hydrogen ion concentration) changes, the currentflowing through the ISFET changes accordingly. Thus, based on themeasurement of the change of the current flow, the ion concentration ofa biological or chemical sample can be determined. For instance, achemical sensing system using ISFET-based chemical sensors can be usedin nucleic acid sequencing applications such as RNA/DNA sequencingapplications.

As shown in FIG. 5D, similar to image sensor 520A, chemically sensitivesensor 520D includes a semiconductor substrate 562, which is the same orsubstantially the same as semiconductor substrate 502 of image sensor520A, respectively, and therefore is not repeatedly described.Chemically sensitive sensor 520D can further include a plurality ofISFETs disposed within an ISFET sensitive area 561. An ISFET includes afloating gate structure 564 disposed above semiconductor substrate 562(e.g., a Silicon substrate). In some embodiments, floating gatestructure 564 is not electrically coupled to an electrode and thuselectrically “floating.” In contrast, a source region and a drain regionof an ISFET are electrically coupled to respective source electrode anddrain electrode (not shown), respectively, and are therefore notelectrically “floating.” In some embodiments, floating gate structure564 includes a first conductive layer 566A, one or more interveningconductive layers 566B-N, and a polysilicon gate 568. The firstconductive layer 566A may be the topmost metal layer and the one or moreintervening conductive layers 566B-N are disposed between firstconductive layer 566A and polysilicon gate 568 as illustrated in FIG.5D.

In some embodiments, chemically sensitive sensor 500D further includes adielectric layer 569 disposed above the floating gate structure 564.Dielectric layer 569 can include at least one of silicon nitride(Si3N4), silicon oxynitride (Si2N2O), silicon oxide (SiO2), aluminumoxide (Al2O3), tantalum pentoxide (Ta2O5), tin oxide or stannic oxide(SnO2). In some embodiments, dielectric layer 569 can include a chargesensitive layer and an adhesion layer. Tantalum pentoxide (Ta2O5) is anexample of a charge sensitive layer, and aluminum is an example ofadhesion layer. In some embodiments, dielectric layer 569 can also serveas a passivation layer, as described above, for protecting chemicallysensitive sensor 520D from liquid or mechanical damage. Dielectric layer569 can be fabricated or disposed by CVD, PVD, atomic layer deposition,or the like.

In some embodiments, one or more openings or wells 565 can be fabricatedor disposed above dielectric layer 569. As illustrated in FIG. 5D, wells565 can be formed by etching an insulation layer 567 (e.g., anotherdielectric layer, polymer layer, or the like). In some embodiments,wells 565 can be formed at least partially inside dielectric layer 569.Wells 565 can be microwells, which has a width in the order ofmicrometers. In some embodiments, first conductive layer 566A includesportions that have dimensions that are substantially the same asdimensions of one or more wells 565. For instance, as shown in FIG. 5D,the width of wells 565 can be substantially the same (or slightlysmaller/larger) than first conductive layer 566A, portions of which arepositioned beneath wells 565 and aligned with corresponding wells 565.

In some embodiments, at least a portion of the biological or chemicalsamples is disposed inside the one or more wells 565. The ionconcentration of biological or chemical samples 565 can be measuredbased on floating gate structure 564 and dielectric layer 569. In thechemical sensing system 500D, no excitation light is required becausethe measurement is with respect to ion concentration. Therefore, anoptical system (e.g., system 304 in FIG. 3) may not be required and isnot shown in FIG. 5D. In chemically sensitive sensor 520D, one of wells565 corresponds to one of floating gate structures 564. The combinationof one well and one floating structure 564 may form a single pixel ofsensor 520D. Similar to those described with respect to image sensors,the more pixels in a chemically sensitive sensor, the higher thethroughput capacity of the sensor.

As described above, the floating gate structure 563 is not electricallycoupled to an electrode. Thus, because the samples are disposed insidewells 565 positioned above floating gate structure 564, the ionconcentration in the samples disposed inside wells 565 causes a chargeaccumulation above the dielectric layer 569. The charge accumulation inturn changes the transistor current flowing through the source and drainareas of the ISFET. Thus, based on the transistor current change, theion concentration can be measured. More details of the structure,operation, and fabrication steps of a chemically sensitive sensor can befound in U.S. Pat. No. 8,936,763, entitled “INTEGRATED SENSOR ARRAYS FORBIOLOGICAL AND CHEMICAL ANALYSIS,” filed on Jun. 1, 2011, the content ofwhich is incorporated by reference in its entirety for all purposes.

Similar to those described in FIG. 5A, TSV packaging and RDLtechnologies can be applied to chemically sensitive sensor 520D toprovide a high throughput or throughput scalable chemical sensingsystem. For example, as shown in FIG. 5D, RDL 516 can be disposed toelectrically couple pads 514 and spheres 518, thereby re-routing signalsfrom pads 514 to spheres 518. Spheres 518 can be further electricallycoupled to an external signal processing circuitry. Similar to theFSI-based image sensor 520C in FIG. 5C, FIG. 5D illustrates that forchemically sensitive sensor 520D, pads 514 are disposed at or near afront surface of a packaged semiconductor die (e.g., the surface at ornear which conductive metal layers for routing signals are disposed).And spheres 518 are disposed at or near a back surface of asemiconductor die (e.g., the surface at or near which no conductivelayers for routing signals is disposed or a surface). Further, groupdicing technology can also be applied to obtain a throughput-scalablechemical sensing system based on chemically sensitive sensor 520D, suchthat multiple chemically sensitive sensors 520D are disposed on packagedsemiconductor dies diced from a wafer as a group. The details of TSVpackaging, RDL routing, and group dicing technologies can be applied ina similar manner as described above, and are thus not repeatedlydescribed here. While FIG. 5D illustrates one chemically sensitivesensor 520D, it is appreciated that multiple chemically sensitivesensors can be included in chemical sensing system 500D. The multiplechemically sensitive sensors can be configured similar to that shown inFIG. 4A or 4B.

With reference back to FIG. 3, in the above description, while sensors320A-N can be implemented as image sensors (e.g., image sensors 520A-C)or chemically sensitive sensors (e.g., chemically sensitive sensor520D), they can also be implemented as other types of sensors such as atransmembrane pore based sensors (sometimes also referred to as nanoporebased sensors). Thus, system 300 can be adapted to a sensing systemusing transmembrane pore based sensors. It is appreciated that one ormore blocks/components shown in FIG. 3 may not be included in atransmembrane pore based sensing system; and additionalblocks/components may be added to such a sensing system. FIG. 5Eillustrates an exemplary transmembrane pore based sensing system 500Ewith a cross-sectional view of an embodiment of a TSV packagedtransmembrane pore based sensor 520E.

A transmembrane pore based sensor is a type of biosensors that candetect a variety of small molecules or ions passing through thetransmembrane pore. A transmembrane pore based sensor can be used in,for example, nucleic acid sequencing applications such as RNA/DNAsequencing applications. For example, in a DNA sequencing application,individual nucleotide incorporation events may be detected. Such eventsmay include incorporation of a nucleotide into a growing strand that iscomplementary to a template. An enzyme (e.g., DNA polymerase) mayincorporate nucleotides to a growing polynucleotide chain. Theincorporated nucleotide is complimentary to the corresponding templatenucleic acid strand, which is hybridized to the growing strand (e.g.,polymerase chain reaction or PCR). The nucleotide incorporation eventsrelease tags from the nucleotides, which pass through a transmembranepore and can be detected.

As illustrated in FIG. 5E, in some embodiments, transmembrane pore basedsensor 520E includes a semiconductor substrate 572, one or moreconductive layers 576 disposed above the semiconductor substrate 572,one or more detection electrodes 578 disposed above the semiconductorsubstrate 572 and conductive layers 576, and a lipid bilayer 575disposed above detection electrodes 578. The semiconductor substrate 572and one or more conductive layers 576 can implement integrated circuitsfor operation of the transmembrane pore based sensor 520E. Suchintegrated circuits may include, for example, amplifiers, integrators,filters, control logic, and/or other circuitry.

In some embodiments, lipid bilayer 575 can be a thin polar membrane madeof two layers of lipid molecules. For example, lipid bilayer 575 caninclude at least one of a planar lipid bilayer, a supported bilayer, ora liposome. Lipid bilayer 575 can be a barrier that keeps ions,proteins, and other molecules where they should be and prevent them fromdiffusing into areas where they should not be. Lipid bilayer 575 mayinclude, or be provided with, one or more transmembrane pores 574.Transmembrane pores 574 can include at least one of protein pores,polynucleotide pores, and solid state pores. Transmembrane pores 574 canhave a dimension that is large enough for passing of molecules (e.g.,tag molecules) and/or small ions (e.g., Na⁺, K⁺, Ca²⁺, Cl⁻) between thetwo sides of lipid bilayers 575. In some embodiments, a fluidic reactionchannel 302 (not shown in FIG. 5E) can be disposed near or above lipidbilayer 575 to provide samples (e.g., nucleic acid molecule and taggednucleotides in liquid reagents) to transmembrane pores 574.

In some embodiments, transmembrane pores 574 can be positionedcorresponding to the positions of the one or more detection electrodes578. Detection electrodes 578 can be coupled to an electrical source andprovide electrical bias or voltage across the two sides of lipid bilayer575, such that molecules or ions can pass through transmembrane pores574. In some embodiments, detection electrodes 578 can further detectelectrical characteristics, such as the change of ion current flow,resistance, capacitance, etc.) of lipid bilayer 575. Based on thedetection of the electrical characteristics, the DNA sequenceinformation can be derived. While FIG. 5E illustrates that detectionelectrodes 578 are used for both applying electrical bias or voltageacross two sides of the lipid bilayers 575 and detecting the electricalcharacteristics of lipid bilayers 575, it is appreciated that, in someembodiments, another pair of electrodes (not shown) can be used to applythe electrical bias or voltage with detection electrodes 578 only beingused for detection of the electrical characteristics. In someembodiments, as illustrated in FIG. 5E, the transmembrane pores basedsensor 520E further includes a passivation layer 579. Passivation layer579 can include one or more openings, and the detection electrodes 578can be disposed within the one or more openings of the passivation layer579. Similar to described above, passivation layer 579 can protecttransmembrane pore based sensor 520E from liquid damage and/ormechanical damage.

In transmembrane pore based sensor 520E, one of transmembrane pores 574,its surrounding portions of lipid bilayer 575, the correspondingdetection electrodes 578 disposed beneath the particular transmembranepore 574, and the corresponding one or more conductive layers 576 mayform a single pixel or sensing unit of sensor 520E. Similar to thosedescribed with respect to image sensors, the more pixels or sensingunits included in a transmembrane pore based sensor, the higher thethroughput capacity of the sensor. More details of the structure,operation, and fabrication steps of a transmembrane pore based sensorcan be found in U.S. Patent Application Publication No. US 2015/0119259,entitled “NUCLEIC ACID SEQUENCING BY NANOPORE DETECTION OF TAGMOLECULES,” filed on Oct. 8, 2014, the content of which is incorporatedby reference in its entirety.

Similar to those described in FIG. 5A, TSV packaging and RDLtechnologies can be applied to transmembrane pore based sensor 520E toprovide a high throughput or throughput scalable transmembrane porebased sensing system. For example, as shown in FIG. 5E, RDL 516 can bedisposed to electrically couple pads 514 and spheres 518, therebyre-routing signals from pads 514 to spheres 518. Spheres 518 can befurther electrically coupled to external signal processing circuitry.Similar to the FSI-based image sensor 520C in FIG. 5C, FIG. 5Eillustrates that for transmembrane pore based sensor 520E, pads 514 aredisposed at or near a front surface of a packaged semiconductor die(e.g., the surface at or near which conductive metal layers for routingsignals are disposed). And spheres 518 are disposed at or near a backsurface of a packaged semiconductor die (e.g., the surface at or nearwhich no conductive layers for routing signals is disposed or asurface). Further, group dicing technology can also be applied to obtaina throughput-scalable sensing system based on transmembrane pore basedsensor 520E, such that multiple transmembrane pore based sensors 520Eare disposed on semiconductor dies diced from a wafer as a group. Thedetails of TSV packaging, RDL routing, and group dicing technologies canbe applied in a similar manner as described above, and are thus notrepeatedly described here. While FIG. 5E illustrates one transmembranepore based sensor 520E, it is appreciated that multiple transmembranepore based sensors can be included in transmembrane pore based sensingsystem 500E. The multiple transmembrane pore based sensors can beconfigured similar to that shown in FIG. 4A or 4B.

With reference back to FIG. 3, sensors 320A-N can be image sensors. Asdescribed above, because image sensors necessarily detect photons, theyare sometimes also referred to as, or used as, photon detection sensors,photon counting sensors, or photoelectron counting sensors in thisdisclosure. Some photon detection sensors can be configured to be moresensitive to, or efficient in collecting, photons. For example, FIG. 5Fillustrates an exemplary photon sensing system 500F with across-sectional view of an embodiment of TSV packaged photon detectionsensor 520F capable of performing a single molecule analysis of abiological or chemical sample. One example of the single moleculeanalysis is a single molecule nucleic acid sequencing analysis. In suchan analysis, a single immobilized nucleic acid synthesis complex isused. The synchesis complex can include a polymerase enzyme, a templatenucleic acid, and a primer sequence that is complementary to a portionof the template nucleic acid. The synthesis complex is disposed as asample and analyzed to identify individual nucleotides as they areincorporated into the extended primer sequence. The incorporation of theindividual nucleotides can be monitored by detecting an opticallydetectable label on the nucleotide associated with an incorporationevent. Unincorporated nucleotides can be removed from the synthesiscomplex, and the labeled incorporated nucleotides (e.g., fluorescentlylabeled) are detected as a part of the immobilized complex. In someembodiments, single molecule primer extension reactions can be monitoredin real-time to identify the continued incorporation of nucleotides inthe extended primer sequence. In such a real-time sequencing (SMRT)analysis, the reaction process of incorporation of nucleotides in theextended primer sequence is monitored as it occurs.

A single molecule analysis of a biological or chemical sample requiresdetecting and/or collecting photons emitted where the intensity orvolume of the photon emissions (e.g., fluorescence emission) can be verylow. Therefore, the photon detection and/or collection efficiencyrequirements can be of great importance in such single moleculeanalysis. Photon sensing system 500F illustrates a system having thecapability of satisfying the photon detection and/or collectionefficiency requirements for such single-molecule analysis. As shown inFIG. 5F, photon detection sensor 520F includes a semiconductor substrate582, a photon detection layer 584 disposed in semiconductor substrate582, and a filter 588. Photon sensing system 500F further includes oneor more optical elements 589 disposed in a light guiding channel 585, afirst optical waveguide 581, a second optical waveguide 583 disposedabove the first optical waveguide 581, and one or more openings or wells587 disposed in second optical waveguide 583.

In some embodiments, one of more wells 587 is configured to receive thebiological or chemical samples, for example, the single immobilizednucleic acid synthesis complex. Wells 587 can be formed as nanoscalewells disposed in second optical waveguide 583. Second optical waveguide583 can be, for example, a zero-mode waveguide. A zero-mode waveguide isan optical waveguide that guides light energy into a sample volume thatis small in all dimensions compared to the wavelength of the light.Thus, second optical waveguide 583 can optically confine orsubstantially confine light being directed to the biological or chemicalsample disposed in wells 587. Second optical waveguide 583 can thereforeform an optical confined area for more efficient illumination of thesample. For example, a small volume of a single immobilized nucleic acidsynthesis complex may be disposed inside a well 587. Because thesynthesis complex is within an optically confined area provided bysecond optical waveguide 583 (e.g., a zero-mode waveguide), theexcitation light 406 can be confined to the synthesis complex. As aresult, the efficiency of illumination can be improved and the singlemolecule analysis can be performed on a small sample volume. In someembodiments, samples disposed at wells 587 can be received from afluidic reaction channel, such as channel 302 shown in FIG. 3. And asdescribed above, a single fluidic reaction channel 302 can be disposedacross, or shared by, multiple sensors such as photon detection sensor520F shown in FIG. 5F.

As shown in FIG. 5F, excitation light 406 for illuminating the samplesdisposed in wells 587 can be directed or guided by first opticalwaveguide 581 to illuminate the sample disposed in one or more wells587. First optical waveguide 581 is similar to optical waveguide 404shown in FIG. 4 and thus not repeatedly described. Similar to thosedescribed above, based on the TSV and group dicing technologies, firstoptical waveguide 581 can be a single optical waveguide disposed acrossa plurality of photon detection sensors similar to photon detectionsensor 520F, such that multiple sensors can share a single opticalwaveguide 581.

With reference to FIG. 5F, in some embodiments, to minimize or reduceloss of emitted light from samples disposed in wells 587, photon sensingsystem 500F includes a light guiding channel 585 configured to directphotons emitted as a result of the single molecule analysis to photondetection sensor 520F. In some embodiments, light guiding channel 585 isdisposed between first optical waveguide 581 and filter 588 of sensor520F. Light guiding channel 585 can include optical elements 589 such asreflective cones, reflective optical lenses, and/or diffractive opticallenses. In some embodiments, optical elements 589 can provide a lightpath for directing photons (e.g., photons of fluorescence light) emittedfrom the samples to filter 588 and underneath photon detection layer 584of photon detection sensor 520F by performing, for example, lightreflection, diffraction, or channeling. In some embodiments, eachbiological or chemical sample is disposed in a well 587, which can bealigned with a corresponding optical element 589 in light guidingchannel 585. The corresponding optical element 589 can further beoptically aligned with a corresponding photosensitive element 584. Thealignment of a well 587, an optical element 589, and a photosensitiveelement 584 can improve the emitted light collection efficiency.

In some embodiments, one or more optical elements 589 can furtherprovide light beam splitting. Optical elements 589 reflective and/ordiffractive lenses that can split the emitted light into multiple beams(e.g., 2, 3, 4 beams). The number of beams provided by optical elements589 can be configured to correspond to the number of photosensitiveelements in photon detection layer 520F. For example, the split beamsmay be configured in a linear manner, or in an array, (e.g., a 2×2 or3×3 array) based on the configuration of the photosensitive elements ofthe photon detection sensor 520F. By splitting the emitted light intomultiple beams, less number of optical elements 589 may be required(e.g., one instead of four).

With reference to FIG. 5F, in some embodiments, photon detection sensor520F includes a filter 588 disposed between the light guiding channel585 and a plurality of photosensitive elements of the photon detectionlayer 584. Filter 588 can include one or more portions, for example,portions 588A and 588B, configured to allow lights having differentwavelength ranges to reach different photosensitive elements of photondetection layer 584. For example, filter portion 588A can be configuredto allow emitted light having a first wavelength range to travel tophotosensitive elements 584A and 584B of photon detection layer 584.Filter portion 588B can be configured to allow emitted light having asecond wavelength range to travel to photosensitive elements 584C and584D of photon detection layer 584. The first wavelength range may bedifferent from the second wavelength range.

The different portions of filter 588 enables detection of differentlabeled incorporated nucleotides (e.g., fluorescently labelednucleotides). For example, emitted fluorescence light based onincorporation of two of the four nucleotides can pass through filterportion 588A to photosensitive elements 584A and 584B (e.g., pixels 584Aand 584B); and emitted fluorescence light based on incorporation of theother two of the four nucleotides can pass through filter portion 588Bto photosensitive elements 584C and 584D (e.g., pixels 584C and 584D).Further, for the emitted fluorescence light that passes through the samefilter portion, the intensity or amplitude of the light may be differentfor different nucleotides. Therefore, based on the different intensityor amplitude, one out of four labeled incorporated nucleotides (e.g.,fluorescently labeled nucleotides) can be determined. The photosensitiveelements 584A-D of photon detection layer 584 can be the same orsubstantially the same as those described above, and are thus notrepeatedly described.

As illustrated in FIG. 5F, optical waveguides 581 and 583, light guidingchannel 585, the filter 588, and photon detection layer 584 of photonsensing system 500F can enable a single molecule analysis using a smallvolume of sample. More details of the structure, operation, andfabrication steps of such a photon sensing system for single moleculeanalysis can be found in U.S. Pat. No. 9,658,161, entitled “ARRAYS OFINTEGRATED ANALYTICAL DEVICES AND METHODS FOR PRODUCTION,” filed on May19, 2016, the content of which is incorporated by reference in itsentirety for all purposes.

Similar to those described in FIG. 5A, TSV packaging and RDLtechnologies can be applied to photon sensing system 500F or photondetection sensor 520F to provide a high throughput or throughputscalable image sensing system. For example, as shown in FIG. 5F, RDL 516can be disposed to electrically couple pads 514 and spheres 518, therebyre-routing signals from pads 514 to spheres 518. Spheres 518 can befurther electrically coupled to external signal processing circuitry. Insome embodiments, photon detection sensor 520F is a BSI-based sensor(e.g., the photosensitive elements 584A-D are disposed closer to sampledisposed in wells 587 than one or more conductive layers 586 fortransmitting electrical signals and implementing signal processingcircuits). Thus, similar to those shown in FIG. 5A, pads 514 can bedisposed at or near a back surface of a packaged semiconductor die(e.g., the surface at or near which no conductive layers for routingsignals is disposed or a surface) or a processing back surface (e.g.,back surface of a thinned die). And spheres 518 are disposed at or neara front surface of a packaged semiconductor die (e.g., the surface at ornear which conductive layers for routing signals are disposed). Further,group dicing technology can also be applied to obtain athroughput-scalable image sensing system based on photon detectionsensor 520F, such that multiple photon detection sensor 520F aredisposed on packaged semiconductor dies diced from a single wafer as agroup. The details of TSV packaging, RDL routing, and group dicingtechnologies can be applied in a similar manner as described above, andare thus not repeatedly described here. While FIG. 5E illustrates onephoton detection sensor 520F, it is appreciated that multiple photondetection sensors can be included in photon sensing system 500F. Themultiple photon detection sensors can be configured similar to thatshown in FIG. 4A or 4B.

With reference back to FIG. 3, throughput-scalable sensing system 300includes a signal and data processing system 330. In some embodiments, asignal processing circuitry of signal and data processing system 330 canbe electrically coupled to one or more sensors 320A-N to receiveelectrical signals (e.g., photoelectrons) generated by sensors 320A-N.In some embodiments, the signal processing circuitry of signal and dataprocessing system 330 can include one or more charge storage/transferelements, an analog signal readout circuitry, and a digital controlcircuitry. In some embodiments, the charge storage/transfer elements(e.g., a charge transfer amplifier) can receive, amplifier, store,and/or read out electrical signals generated in sequence or in parallelby the photosensitive elements of a sensor 320 (e.g., using a rollingshutter or a global shutter); and transmit the received electricalsignals to the analog signal read-out circuitry. The analog signalread-out circuitry may include, for example, an analog-to-digitalconverter (ADC), which converts analog electrical signals to digitalsignals.

In some embodiments, the signal processing circuitry of signal and dataprocessing system 330 can include a rolling shutter, which enablessequential readout of electrical signals generated by the photosensitiveelements of a sensor 320. A rolling shutter exposes different rows of aphotosensitive elements array (e.g., a pixel array) of a sensor atdifferent times and reads out in a chosen sequence. In a rollingshutter, although each row of the photosensitive elements array of thesensor may be subject to the same exposure time, the rows at the top ofthe photosensitive elements array of the sensor may end the exposurebefore the rows at the bottom of the photosensitive elements array ofthe sensor. This may lead to spatial distortion, especially for largescale image sensing systems. However, because each sensor 320A-N insensing system 300 is disposed on a separate semiconductor die using thegroup dicing technology, these sensors 320 shown in FIG. 3 can besmall-to-medium scale sensors independent from other sensors. Asdescribed above, the group dicing technology reduces or avoids therequirements for large scale image sensing system using a large singlepixel array for a sensor. Instead, sensing system 300 can includemultiple small-medium size pixel arrays. As a result, a rolling shuttercan be used in a throughput-scalable sensing system described (e.g.,system 300) in this disclosure without spatial distortion or withreduced spatial distortions.

In some embodiments, the signal processing circuitry of signal and dataprocessing system 330 can include a global shutter, which enables asubstantial concurrent readout of electrical signals generated by thephotosensitive elements of the sensors 320. Using a global shutter canimprove the signal readout speed over a rolling shutter. A globalshutter can expose all photosensitive elements (e.g., pixels)simultaneously or concurrently. At the end of the exposure, thecollected charge or electrical signal can be transferred to the readoutnodes of the analog signal readout circuitry simultaneously or atsubstantially the same time. As a result, a global shutter eliminates orreduces spatial distortion, especially for large scale sensing systems.In some embodiments, eliminating or reducing spatial distortion can havesignificantly positive impact on high-throughput nucleotide sequencing,which frequently relies on high-resolution detection of large amounts offine targets at high density. Global shutter techniques can improve theaccuracy of co-registration of a large quantity (e.g., millions) of DNAimage spots on many (e.g., thousands) sequencing images repeatedlyrecorded at different testing times.

The above described rolling shutter or global shutter typically operatesat a fixed rate in exposing photosensitive elements and transferred thecollected charge or electrical signals to readout nodes. In someembodiments, the signal processing circuitry of signal and dataprocessing system 330 can include an event triggered shutter. An eventtriggered shutter does not operate in a fixed rate. Instead, it iscapable of selectively reading out of electrical signals generated byphotosensitive elements of sensors 320. FIG. 6 is a block diagram 600illustrating an exemplary event-triggered shutter. As shown in FIG. 6, aphoton collection unit 602 can be controlled to collect photons of thelight from the samples being analyzed at certain integration time. Thecollection of photons is sometimes also referred to as photosensitiveelement exposure. The photons collected over a predetermined integrationtime can be converted, by the photosensitive elements, to photoelectronsor electrical signals. An event-triggered shutter can include a sampleand hole circuit 604 and a detection circuit 606. Sample and holdcircuit 604 can provide the electrical signals in the form of an outputvoltage. This output voltage can be provided to detection circuit 606 ofthe event-triggered shutter. In some embodiments, detection circuit 606can include a voltage comparator that compares the output voltage to athreshold voltage. If the output voltage is greater than the thresholdvoltage, the collected charge or electrical signal (e.g., the outputvoltage) can be transferred to the readout nodes of the analog signalreadout circuitry. Thus, detection circuit 606 of the event-triggeredshutter can selectively read out electrical signals generated by thephotosensitive elements based on a result of the comparison of an outputvoltage with a threshold voltage.

An event-triggered shutter provides several advantages. For example,instead of blindly reading out all the electrical signals generated bythe photosensitive elements, signals can be selectively read out foronly effective events. This is particularly beneficial forchemiluminescence light detection, because electrical signals generatedbased on chemiluminescence light detection may not be produced at afixed rate. Therefore, reading out such electrical signals at a fixedrate would unnecessarily increase data flow and impose extra processingburden on the signal and data processing circuitry. Further,event-triggered shutter can enable flexible signal readout by adjustingintegration time and/or threshold voltages. For instance, by increasingintegration time and/or reducing threshold voltage, low intensity lightemissions can be detected (e.g., for analysis of samples having smallvolumes such as single molecule analysis, or single photon detection asdescribed more in detail below). Therefore, an event-triggered shuttercan enable reading out of both strong and weak electrical signals(corresponding to high and low light intensity light emissions).Further, in some embodiments, each photosensitive element (e.g., eachpixel) can be configured to have one integration time using theevent-triggered shutter. Thus, each photosensitive element can haveexposure independent of other photosensitive elements, thereby improvingthe flexibility of reading out electrical signals for different pixelsin a pixel array of a sensor.

In addition to a signal processing circuitry, signal and data processingsystem 330 shown in FIG. 3 can include a data processing system. Afterthe signal processing circuitry converts analog electrical signals todigital signals (e.g., using an ADC), it can transmit the digitalsignals to the data processing system for further processing. Forexample, the data processing system can perform various digital signalprocessing (DSP) algorithms (e.g., compression) for high-speed dataprocessing. In some embodiments, at least part of the data processingsystem can be integrated with the signal processing circuitry on a samesemiconductor die or chip. In some embodiments, at least part of thedata processing system can be implemented separately from the signalprocessing circuitry of system 330 (e.g., using a separate DSP chip orcloud computing resources). Thus, data can be processed and sharedefficiently to improve the performance of the sample analytical system.It is appreciated that at least a portion of the signal processingcircuitry and the data processing system of signal and data processingsystem 330 can be implemented using, for example, CMOS-based applicationspecific integrated circuits (ASIC), field programmable gate array(FPGA), discrete IC technologies, and/or any other desired circuittechniques.

With reference to FIG. 3, in some embodiments, one or more sensors 320can be photon counting image sensors such as quanta CMOS image sensors(QISs). A QIS has very small photosensitive elements (e.g., 100-1000 nmpitch) with small full well capacity (e.g., 1-200 carriers). A QISphotosensitive element is also referred to as sub-diffraction limit(SDL) photosensitive element. An SDL photosensitive element can besensitive to single photoelectrons, such that the presence or absence ofone photoelectron results in a logical binary output of 0 or 1 atreadout. An SDL photosensitive element is also frequently referred to asa “jot” device (Greek for “smallest thing”). And a QIS may include manyphotosensitive elements to generate hundreds, thousands, or millions ofoutputs (e.g., binary bits of 0s and 1s). The outputs from thephotosensitive elements can form two dimension or three-dimensionalarrays. For example, at any given time, a plurality of QISphotosensitive elements can provide 16×16 array of outputs (or any sizearray depending on the two spatial dimensions of the QIS photosensitiveelements). Such an array of outputs can form a bit plane, eachcorresponding to a field. Multiple bit planes generated by the pluralityof QIS photosensitive elements at different time can form a data cubehaving a three-dimensional array (e.g., a 16×16×16) with the thirddimension being the temporal dimension.

In some embodiments, a single image pixel can be generated based on oneor more such two-dimensional or three-dimensional arrays generated bythe plurality of QIS photosensitive elements. For example, signal anddata processing system 300 can process the 16×16×16 data cube andgenerate a single image pixel, which represents a local light intensityreceived by the QIS photosensitive elements. Accordingly, by adjustingor configuring the size of the two-dimensional arrays orthree-dimensional arrays, the output image pixel size of a QIS isprogrammable for trading resolution with sensitivity. For example, ifmore QIS photosensitive element outputs (e.g., a large data cube) areincluded for generating a single image pixel, the light intensity isincreased and the sensitivity of the QIS can be enhanced. And if lessQIS photosensitive element outputs (e.g., a large data cube) areincluded for generating a single image pixel, the resolution of theoutput image may be increased with a reduced sensitivity. It is alsoappreciated that different image pixels may be generated based on datacubes of different sizes and the multiple data cubes may overlap.

A QIS is one type of photon counting sensors or photoelectron-countingsensors that are capable of detecting a single photon. Other types ofphoton-counting sensors (e.g., sCMOS, EMCCD, or SPAD) often requireavalanche multiplication to achieve high conversion gain. Thus,fabrication of these types of photon-counting sensors can requirespecial processes that are complex and costly. A QIS is compatible withstandard CMOS image sensor fabrication process. Further, as describedabove, a QIS has very small photosensitive elements (e.g., 100-1000 nmpitch) with small full well capacity (FWC). Thus, a QIS photosensitiveelement can have high conversion gain, low readout noise, and low darkcurrent. As a result, a QIS does not require those complex, special, andcostly processes used in other types of photon-counting sensors.

FIG. 7A illustrates an exemplary QIS-based sensing system 700 with across-sectional view of an embodiment of a TSV packaged QIS 720. Similarto FIG. 5A, QIS-based sensing system 700 can be a BSI-based sensingsystem including a QIS 720, a fluidic reaction channel 302 and opticalsystem 304 (not shown in FIG. 7A). Fluidic reaction channel 302 andoptical system 304 can be substantially the same as those describedabove and are thus not repeatedly described. Similar to a BSI-basedimage sensor described above, QIS 720 can include a plurality of QISphotosensitive elements 704 (e.g., SDL photosensitive elements). In someembodiments, as shown in FIG. 7A, a fluidic reaction channel 302 canprovide samples that are disposed in openings or wells 774. Wells 774can be positioned above corresponding QIS photosensitive elements 704for performing a nucleotide acid sequencing analysis. For example, thesample can be a single immobilized nucleic acid synthesis complex usedfor a single molecule sequencing analysis. It is appreciated thatfluidic reaction channel 302 can also provide samples for other types ofsequencing analysis such as cluster sequencing analysis. In someembodiments, similar to those described above, fluidic reaction channel302 can be disposed across multiple QISs, with each disposed on asemiconductor die of a single semiconductor wafer. In some embodiments,fluidic reaction channel 302 can be disposed separately to providesamples (e.g., synthesis complex) to wells 774 positioned above multipleQISs.

As described above, QIS-based sensing system 700 includes a plurality ofQISs, such as QIS 720. QIS 720 can include many (e.g., thousands ormillions) QIS photosensitive elements 704 (e.g., SDL photosensitiveelements). An exemplary QIS photosensitive element 704A is illustratedin FIG. 7B. In some embodiments, QIS photosensitive element 704A can bea pinned photodiode based photosensitive element. As illustrated in FIG.7D, QIS photosensitive element 704A can include a charge transfer gate722 disposed above a semiconductor substrate 702 of a semiconductor die.QIS photosensitive element 704A can further include a pinned photodiode724 disposed in semiconductor substrate 702 at a first side (e.g., leftside as shown in FIG. 7B) of charge transfer gate 722. QISphotosensitive element 704A can further include a floating diffusionnode 726 disposed in semiconductor substrate 702 at a second side (e.g.,right side as shown in FIG. 7B) of the charge transfer gate 704. Pinnedphotodiode 724 can detect photons and generate photoelectrons based onthe detected photons. Upon applying a proper potential on chargetransfer gate 704, the charges of the photoelectrons can be transferredto floating diffusion node 726. Thus, the combination of charge transfergate 722, pinned photodiode 724, and floating diffusion nodes 726 candetect photons and transfer the photoelectron charges to be subsequentlyread out. In some embodiments, QIS photosensitive element 704A canfurther include a readout circuitry (e.g., a source follower) and otherlogics (e.g., reset logic), some of which are shown in FIG. 7B.

In FIG. 7B, charge transfer gate 722 and floating diffusion node 726 maybe overlapped spatially. The capacitance of floating diffusion node 726can include depletion capacitance between floating diffusion node 726and semiconductor substrate 702, overlap capacitance between floatingdiffusion node 726 and charge transfer gate 722, overlap capacitancebetween floating diffusion node 726 and a reset gate 727, and othercapacitances (e.g., source-follower gate capacitance, inter-metalcapacitance, etc.). To improve the conversion gain of the QISphotosensitive element, overlap capacitance between floating diffusionnode 726 and charge transfer gate 722 needs to be reduced, because theconversion gain is reversely proportional to the capacitance of floatingdiffusion node 726.

FIG. 7C illustrates another QIS photosensitive element 704B with reducedoverlap capacitance. As shown in FIG. 7C, QIS photosensitive element704B includes a charge transfer gate 742 and a floating diffusion node746. Charge transfer gate 742 and floating diffusion node 746 are notspatially overlapped so that the overlap capacitance is reduced. In QISphotosensitive element 704B, different diffusion areas (e.g., areas 743and 745) with proper implantation or carrier concentration insemiconductor substrate 702 are configured to have different dopingconcentrations. Photoelectrons can be detected and accumulated in onearea (e.g., area 743 that is associated with a photodiode) of thesemiconductor substrate 702. When a proper potential is applied oncharge transfer gate 742 and therefore the charge transfer gate 742 isturned on, the charges of the accumulated photoelectrons can betransferred from area 743 to another area 745 of semiconductor substrate702. Area 745 can be directly under the charge transfer gate 742. Thecharges can then be transferred to floating diffusion node 746 in a pumpaction when the charge transfer gate 742 is turned off. It isappreciated that a QIS photosensitive element is not limited to theabove described elements 704A and 704B. Other types of QISphotosensitive elements (e.g., a junction FET based on element) can alsobe used in a QIS.

With reference back to FIG. 7A, similar to those described in FIG. 5A,TSV packaging and RDL technologies can be applied to QIS-based sensingsystem 700 or QIS 720 to provide a high throughput or throughputscalable image sensing system. For example, as shown in FIG. 7A, RDL 716can be disposed to electrically couple pads 714 and spheres 718, therebyre-routing signals from pads 714 to spheres 718. RDL 716 is partiallyenclosed by through-hole vias 712. Spheres 718 can be furtherelectrically coupled to external signal processing circuitry such asreadout circuitry as described in more detail below. In someembodiments, as described above, QIS 720 is a BSI-based sensor (e.g.,the QIS-based photosensitive elements 704 are disposed closer to sampledisposed in wells 774 than conductive layers 706 for transmittingelectrical signals and implementing signal processing circuits). Thus,similar to those shown in FIG. 5A, pads 714 can be disposed at or near aback surface of a semiconductor die (e.g., the surface at or near whichno conductive layers for routing signals is disposed or a surface) or asurface of a thinned die. And spheres 718 are disposed at or near afront surface of a semiconductor die (e.g., the surface at or near whichconductive metal layers for routing signals are disposed) or a surfaceof a carrier wafer 701. Further, group dicing technology can also beapplied to obtain a throughput-scalable QIS-based photon sensing systembased on QIS 720, such that multiple QISs 720 are disposed onsemiconductor dies diced from a single wafer as a group. The details ofTSV packaging, RDL routing, and group dicing technologies can be appliedin a similar manner as described above, and are thus not repeatedlydescribed here.

As described above, a QIS-based photosensitive element 704 can include areadout circuitry (e.g., a source follower) for reading out the chargetransferred to a floating diffusion node. In some embodiments, theoutput from a QIS-based photosensitive element can be transmitted toexternal signal processing circuitry for further processing. FIG. 7Dillustrates such a signal processing circuitry 760. In some embodiments,signal processing circuitry 760 can include a correlated double sampling(CDS) circuit 762 configured to sample an output voltage signal of oneof more QIS-based photosensitive elements. The sampled output voltagesignal can be transmitted to a sense amplifier 764 electrically coupledto the correlated double sampling circuit 762. Sense amplifier 764 canamplify small signals (e.g., signals having small amplitude) tologically distinguishable signals. The output signals from senseamplifier 764 can be transmitted to an analog to digital converter 766for converting analog signals to digital signals. Signal processingcircuitry 760 may include other circuitry such as digital kernel 767 andmemory 768, for further digital signal processing, buffering, andstoring of the data.

In some embodiments, group dicing and wafer level bonding technologiescan be used with a QIS-based sensing system. FIG. 7E illustrateswafer-level prospective diagrams and corresponding block diagrams of anembodiment of an exemplary QIS-based sensing system 780. As shown inFIG. 7E, using the group dicing technology described above, system 780can include a plurality of semiconductor dies separated from a firstsemiconductor wafer 781 and a plurality of semiconductor dies separatedfrom a second semiconductor wafer 783. The dies can be separated asgroups as described above using group dicing technology. In someembodiments, QIS photosensitive elements (e.g., SDL photosensitiveelements or “jots”) can be fabricated or disposed on the dies of firstsemiconductor wafer 781 and therefore wafer 781 may also be referred toas the detection wafer. In some embodiments, signal processing circuitrysuch as readout circuits can be fabricated or disposed on the dies ofsecond semiconductor wafer 783, and therefore wafer 783 may also bereferred to as the signal processing wafer or ASIC wafer. In someembodiments, QIS photosensitive elements of wafer 781 can beelectrically coupled to the signal processing circuitry of wafer 783using wafer level packaging technologies, such as the TSV and RDLtechnologies as described above. For example, the TSV and RDLtechnologies can be applied to detection wafer 781 such that spheres(e.g., solder balls), instead of wire bonding, are used to electricallycouple devices on wafer 781 to devices on wafer 783. Wafer levelpackaging technologies can thus enable a high density and large scaleQIS-based sensing system.

As illustrated in FIG. 7E, in some embodiments, each semiconductor dieof wafer 781 can include a QIS having many QIS-based photosensitiveelements. A group or array of QIS can form a QIS cluster 784 anddetection wafer 781 can include many QIS clusters. Similarly, eachsemiconductor die of wafer 783 can include a signal processing circuitry760 for one or more corresponding QIS, such as readout circuits. Asdescribed above, signal processing circuitry 760 can include, forexample, a CDS 762, a sense amplifier 764, an ADC 766, and othercircuits 767 and 768. More details of the structure, operation, andfabrication steps of a QIS can be found in “The Quanta Image Sensor:Every Photon Counts” by Eric R. Fossum et al. Published by Sensors, MDPIjournal on Aug. 10, 2016, the content of which is incorporated byreference in its entirety for all purposes.

As described above, a sensing system obtained based on group dicing mayresult in an image having image gaps due to the physical separations ofsensors by the dicing streets (and other structures). Thus, an imagegenerated by QIS-based photo sensing system 700 shown in FIG. 7A mayhave image gaps because group dicing is used for fabricating such asystem. While image gaps may be unacceptable in some applications, theyhave no or minimum impact on the performance on a sensing system that isused for a biological or chemical sample analysis applications (e.g., anucleotide acid sequencing application). For many biological or chemicalsample analysis application, QIS-based sensing system 780 can be used tocount photons emitted from the samples. And the analysis results areoften based on the information related to photon counting (e.g., theintensity of photons, position of photons, pattern of photons, etc.).Therefore, a high-throughput scalable sensing system including multiplegroup-diced QISs can be readily used for many biological or chemicalsample analysis applications or any other photon counting basedapplications, without having to make mitigation effort to remove thegaps or stitch portions of the images together.

FIGS. 8A-8G illustrate cross-sectional views associated with processingsteps for fabricating a throughput-scalable sensing system such assystems 300, 500A-F, and 700. It is appreciated that the processingsteps shown in FIGS. 8A-8G may not include all steps and may havevariations. The cross-sectional views may not illustrate all elements ofthe throughput-scalable sensing system and may not be drawn to scale.For illustration purposes, the fabrication process shown in FIGS. 8A-8Guses BSI-based image sensing system as an example. It is appreciatedthat the fabrication process shown in FIGS. 8A-8G, or a variationthereof, can be applied to any sensing system described above, such asan FSI-based image sensing system, a chemically sensitive sensor basedsensing system, a transmembrane pore sensor based sensing system, aphoton detection sensor based sensing system, and a QIS based sensingsystem.

With reference to FIG. 8A, in some embodiments, two wafers 802 and 804are received for fabricating a throughput-scalable sensing system. Wafer802 can include a semiconductor substrate 806 (e.g., a Siliconsubstrate) and a plurality of sensors. FIG. 8A illustrates two suchsensors 810A and 810B. For illustration purposes, sensors 810A and 810Bare illustrated as BSI-based image sensor in FIGS. 8A-8G. It isappreciated that sensors 810A and 810B can be any of the sensorsdescribed above. As shown in FIG. 8A, sensors 810A and 810B can includea photon detection layer that includes a plurality of photosensitiveelements, filter, conductive layers for implementing readout circuitsand other circuits as described above, dielectric layers (e.g., SiO2 forisolating the conductive layers from one another), and/or a passivationlayer. In some embodiments, sensors 810A and 810B are fabricated ordisposed in two separate semiconductor dies of wafer 802, and areelectrically isolated from each other (e.g., by field oxide). Thefabrication of these sensors can use, for example, standard CMOS imagesensor (CIS) process or any suitable processes for the different typesof sensors as described above.

As illustrated in FIG. 8A, in some embodiments, prior to receiving wafer802, semiconductor substrate 806 of wafer 802 can be thinned from a backsurface of wafer 802. Thinning of back surface can be required for aBSI-based image sensor, but may not be required for an FSI-based imagesensor or other type of sensors. As described above and shown in FIGS.3, 4, and 5A, an optical system (e.g., a waveguide) may be disposed onthe back surface to direct the excitation light to the samples; and thesamples may be disposed on the optical system. The light emitted fromthe samples travels to the photosensitive elements in the semiconductorsubstrate. Thus, thinning of the semiconductor substrate 806 from theback surface of wafer 802 can reduce the distance the light emitted fromthe samples has to travel. As a result, the light collection anddetection efficiency of the sensors 810A-B can be improved. As used inthis disclosure, the front surface of a wafer is a surface at or nearwhich one or more conductive layers and one or more dielectric layersare disposed; and the back surface of a wafer is a surface opposite tothe front surface. The back surface is usually a semiconductor substratesurface. In some embodiments, a passivation layer 812 can be depositedon the thinned back surface 816 of wafer 802. Thinning of wafer 802 canbe performed using, for example, chemical-mechanical polishing orplanarization (CMP), mechanical thinning, and/or wet or dry etching(isotropic etching or anisotropic etching). Similar to those describedabove, passivation layer 812 can provide protection of wafer 802 fromliquid damage and/or mechanical damage. Passivation layer 812 can bedeposited using CVD, PVD, or any other depositing process.

In some embodiments, as shown in FIG. 8A, wafer 802 can be bonded withwafer 804. As described above, in some embodiments, wafer 802 is thinned(e.g., for fabricating BSI-based image sensing system) and therefore maybe fractured or damaged during the subsequent processing steps. Wafer804 can be a carrier wafer to provide support for wafer 802 to reduce oreliminate the likelihood that the wafer 802 is damaged during thesubsequence processing steps. As shown in FIG. 8A, bonding of wafer 802and wafer 804 can be performed at the front surface 818 (e.g., thesurface that is disposed with conductive layers and dielectric layers)of wafer 802 and at surface 820 of carrier wafer 804. It is appreciatedthat wafer 804 may be optional for certain type of sensors that do notrequire thinning of wafer 802 (e.g., FSI-based image sensors). If wafer802 is not thinned, it may not require extra support and thus a carrierwafer may not be required. Wafers 802 and 804 can be bonded using anysuitable wafer bonding technologies including direct bonding, surfaceactivated bonding, adhesive bonding, thermocompression bonding, etc.

In some embodiments, wafer 802 may be stacked with a third wafer (notshown). As described above, the group dicing technology described inthis disclosure enables a sensing system to be easily scaled or stackedup to provide parallel signal and data processing in a large-scalesensing application (e.g., 100 meg-1 giga image sensing application).Thus, two or more wafers can be stacked such that the sensing system ismore compact. One example of stacking wafers is illustrated in FIG. 7Eand described above. For instance, wafer 781 (e.g., a detection wafer)and wafer 783 (a signal processing wafer) can be stacked with each otherfor providing a large scale QIS-based sensing system.

After bonding wafers 802 and 804, they are prepared for conductive pathredistribution. FIGS. 8A-8C illustrate the processes for preparingbonded wafers 802 and 804 for conductive path redistribution. Asdescribed above, conductive path redistribution renders input/outputpads (e.g., pads 814) of an integrated circuit or device (e.g., sensors810A-B) available in other locations. As shown in FIGS. 8A and 8B, adetachable glass substrate 822 can be adhesively bonded to wafer 802.The bonding of glass substrate 822 can use bonding adhesives 823 tomechanically attach glass substrate 822 to wafer 802. In someembodiments, the bonding adhesives can be soluble so that glasssubstrate 822 can be detached from wafer 802 after the conductiveredistribution paths are formed.

In addition to bonding glass substrate 822, preparing wafers 802 and 804for conductive path redistribution can also include thinning a portionof wafer 802 and a portion of wafer 804. FIGS. 8B-8C illustratecross-section views of the wafers before and after the thinning process.In some embodiments, as shown in FIG. 8B, wafer 804 can be thinned fromsurface 824. Surface 824 is opposite to the bonded interface betweenwafer 802 and wafer 804. Thinning can be performed usingchemical-mechanical polishing or planarization (CMP), mechanicalthinning, and/or wet or dry etching (isotropic etching or anisotropicetching). In some embodiments, thinning of wafer 802 can be performed toremove semiconductor substrate of a certain thickness or thicknessrange. The thinning can be isotropic or substantially the same acrosswafer 802.

In some embodiments, following an isotropic thinning of wafer 802, adirectional or anisotropic etching can be performed. For example, afirst mask layer (not shown) can be deposited to define areas 826 foranisotropic etching. Anisotropic etching can then be performed to removematerials in the defined areas 826. For example, as shown in FIG. 8C,anisotropic etching can further remove a portion of the semiconductorsubstrate of wafer 804, dielectric layers of wafer 802, and a portion ofsemiconductor substrate of wafer 802. Anisotropic etching can beperformed by wet etch or dry etch processes. After the anisotropicetching process, the first mask layer (e.g., a photoresist layer) can beremoved.

After preparing the wafer 802 and wafer 804 for conductive pathredistribution, one or more redistribution paths can be formed. In FIG.8C, through-hole vias 828 are formed in the semiconductor substrate 806of thinned wafer 802. Forming through-hole vias 828 can be performed by,for example, anisotropic etching (e.g., dry etching) of semiconductorsubstrate 806. For example, a second mask layer can be deposited todefine areas to be etched from the semiconductor substrate 806 of wafer.The defined areas can correspond to areas above theelectrically-conductive pads 814. Based on the defined areas, a portionof the semiconductor substrate 806 of wafer 802 can be etched to formthrough-hole vias (e.g., through-silicon vias). The through-hole viasexpose at least a portion of the electrically-conductive pads 814 suchthat pads 814 can be electrically coupled to a redistribution layer.After forming the through-hole vias, the second mask layer (e.g., aphotoresist layer) can be removed.

FIG. 8D illustrates depositing a redistribution layer 830.Redistribution layer 830 includes conductors (e.g., metals) at leastpartially enclosed by through-hole vias 828. In some embodiments, beforedepositing the conductors, a third mask layer (not shown) can bedeposited to define pre-determined areas corresponding to one or moreredistribution paths. Based on the defined pre-determined areas, one ormore conductors can be deposited. The conductors can be metal-basedconductors deposited using PVD (e.g., sputtering), CVD, PECVD, etc.Portions of the conductors of redistribution layer 830 can be depositedinside through-hole vias 828 and thus are partially enclosed by thecorresponding through-hole vias 828. The conductors can be in contactwith the corresponding electrically-conductive pads 814 disposed atsurface 816 of the wafer 802. The conductors can extend from pads 814 toreroute electrical signals to desired areas. After the redistributionlayer 830 has been deposited, the third mask layer can be removed.

FIG. 8E illustrates forming a plurality of electrically-conductivespheres 818. As shown in FIG. 8E, before disposing spheres 818 (e.g.,solder balls), a solder mask layer 832 can be deposited in contact withthe redistribution layer 830 and other areas of the wafers 802 and 804(e.g., back surface 834 where no redistribution layer 830 is deposited).A solder mark layer can be, for example, a thin layer of polymer forprotection the redistribution layer 830 against oxidation and forpreventing solder bridges from forming between closely spaced conductorsor spheres. Next, a fourth mask layer can be deposited to define areascorresponding to areas for attaching the electrically-conductive spheres818. Based on the defined areas, the solder mask layer can be etched toremove portions of the solder mask layer such that the underneathconductors of the redistribution layer 830 are exposed. The exposedconductors of the redistribution layer 830 can be in contact withspheres 818 for electrical coupling. Subsequent to the etching, thefourth mask layer can be removed. The electrically-conductive spheres818 can be disposed at the areas defined for attaching theelectrically-conductive spheres 818 (e.g., areas above the exposedconductors of the redistribution layer 830). As a result, theredistribution layer 830 electrically couples the plurality ofelectrically-conductive pads 814 to the plurality ofelectrically-conductive spheres 818. Thus, electrical signals can beredistributed or re-routed from pads 814 to spheres 818, which can thenbe electrically coupled to external signal processing circuitry. Asdescribed above, the signal redistribution or rerouting enables a morecompact, effective, or efficient packaging for large scale sensingsystem, without the requirement of using wiring bonding.

FIG. 8F illustrates a process of removing detachable glass substrate822, which is adhesively bonded to wafer 802. As described above, glasssubstrate 822 is used to provide support to bonded wafers 802 and 804 sothat the wafers may not be fractured or damaged during the processingsteps. After the processes described above are completed, glasssubstrate 822 can be removed by, for example, dissolving the adhesivefor bonding wafer 802 to glass substrate 822.

After the glass substrate 822 is removed, an array of semiconductor diescan be diced as a group from the plurality of semiconductor dies ofprocessed wafer 802, which is bonded with processed wafer 804. The arrayof semiconductor dies includes a group of sensors associated with thethroughput-scalable sensing system. FIG. 8G illustrates such a dicingprocess. FIG. 8G is the same or substantially the same as FIG. 2C, andthus is not repeatedly described.

FIG. 9 is a flow diagram illustrating an exemplary method 900 forfabricating a throughput-scalable sensing system. In step 902 of method900, a first semiconductor wafer (e.g., wafer 802 of FIG. 8A) and secondsemiconductor wafer (e.g., wafer 804 of FIG. 8A) are received. The firstsemiconductor wafer includes a semiconductor substrate and a pluralityof sensors disposed in the semiconductor substrate. Each sensor of theplurality of sensors is disposed in a separate semiconductor die of thefirst semiconductor wafer.

At step 904, the first semiconductor wafer to the second semiconductorwafer are bonded together. FIG. 8B illustrates such a bonding process.

At step 906, the bonded first semiconductor wafer and the secondsemiconductor wafer is prepared for conductive path redistribution. FIG.8C illustrates the processes for preparing the bonded wafers forconductive path redistribution.

At step 908, one or more redistribution paths are formed from aplurality of electrically-conductive pads disposed at a first surface ofthe prepared first semiconductor wafer to a plurality ofelectrically-conductive spheres disposed at a first surface of theprepared second semiconductor wafer. The one or more redistributionpaths are partially enclosed by one or more through-hole vias. FIGS.8D-8E illustrates the forming of redistribution paths.

At step 910 an array of semiconductor dies is diced as a group from aplurality of semiconductor dies. The array of semiconductor diesincludes a group of sensors associated with the throughput-scalablesensing system. FIGS. 8F and 2C illustrate the group dicing process.

It is understood that the specific order or hierarchy of blocks in theprocesses and/or flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the block diagrams, processesand/or flowcharts may be rearranged. Further, some blocks may becombined or omitted. The accompanying method claims present elements ofthe various blocks in a sample order, and are not meant to be limited tothe specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed under 35 U.S.C. § 112(f) unless the elementis expressly recited using the phrase “means for.”

1-66. (canceled)
 67. A throughput-scalable sensing system, comprising: aplurality of semiconductor dies sharing a common semiconductorsubstrate; a plurality of transmembrane pore based sensors configured todetect a change of current flow as a result of analyzing biological orchemical samples, a plurality of dicing streets separating the pluralityof semiconductor dies from one another, wherein each dicing street ofthe plurality of dicing streets comprises an indented area between twoimmediately neighboring semiconductor dies, the indented areafacilitating separation of the two immediately neighboring semiconductordies; wherein two immediately neighboring transmembrane pore basedsensors of the plurality of transmembrane pore based sensors arearranged on respective two semiconductor dies separated by a dicingstreet of the plurality of dicing streets, wherein each transmembranepore based sensor of the plurality of transmembrane pore based sensorsis arranged on a separate semiconductor die of the plurality ofsemiconductor dies, and wherein at least one transmembrane pore basedsensor of the plurality of transmembrane pores based sensors comprises:one or more detection electrodes disposed above the common semiconductorsubstrate, the one or more detection electrodes being capable ofdetecting the change of current flow, a lipid bilayer disposed above theone or more detection electrodes, the lipid bilayer including one ormore transmembrane pores positioned corresponding to the positions ofthe one or more detection electrodes.
 68. The system of claim 67,wherein the number of transmembrane pore based sensors of the pluralityof transmembrane pore based sensors is determined based on a throughputscaling requirement for the throughput-scalable sensing system and basedon a throughput capacity of each transmembrane pore based sensor of theplurality of transmembrane pore based sensors.
 69. The system of claim67, wherein the plurality of transmembrane pore based sensors areelectrically isolated from one another.
 70. The system of claim 67,wherein the at least one transmembrane pore based sensor of theplurality of transmembrane pore based sensors further comprises one ormore through-hole vias at least partially enclosing conductors of aredistribution layer.
 71. The system of claim 70, wherein the conductorselectrically couple electrically-conductive pads and correspondingelectrically-conductive spheres.
 72. The system of claim 71, wherein theplurality of transmembrane pore based sensors comprises silicon-basesensors.
 73. The system of claim 71, wherein the one or morethrough-hole vias comprise one or more through-silicon vias.
 74. Thesystem of claim 71, wherein the electrically-conductive pads and theelectrically-conductive spheres are electrically coupled only by thecorresponding conductors of the redistribution layer.
 75. The system ofclaim 67, wherein the one or more transmembrane pores comprise proteinpores.
 76. The system of claim 67, wherein the one or more transmembranepores comprise polynucleotide pores.
 77. The system of claim 67, whereinthe one or more transmembrane pores comprise solid state pores.
 78. Thesystem of claim 67, wherein the lipid bilayer comprises a planar lipidbilayer.
 79. The system of claim 67, wherein the lipid bilayer comprisesa supported bilayer.
 80. The system of claim 67, wherein the lipidbilayer comprises a liposome.
 81. The system of claim 67, wherein the atleast one transmembrane pore based sensor of the plurality oftransmembrane pore based sensors further comprises a passivation layerincluding one or more openings, wherein the one or more detectionelectrodes are disposed within the one or more openings of thepassivation layer.